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CI 



NORTH CAROLINA 
DEPARTMENT OF CONSERVATION AND DEVELOPMENT 

GEORGE R. ROSS, DIRECTOR 



DIVISION OF MINERAL RESOURCES 

JASPER L. STUCKEY, STATE GEOLOGIST 



Bulletin Number 62 



Feldspar Deposits of The Bryson City District, 

forth Carolina 



BY EUGENE N. CAMERON 



PREPARED BY GEOLOGICAL SURVEY, U. S. DEPARTMENT OF THE INTERIOR 

IN COOPERATION WITH THE 
NORTH CAROLINA DEPARTMENT OF CONSERVATION AND DEVELOPMENT 



RALEIGH 
1951 



North Carolina 
Department of Conservation and Development 

George R. Ross, Driector 



Division of Mineral Resources 

Jasper L. Stuckey, State Geologist 



Bulletin Number 62 



Feldspar Deposits of the Bryson City District, 

North Carolina 



By 
Eugene N. Cameron 



Prepared by Geological Survey, U. S. Department of the Interior 

In cooperation with the 

North Carolina Department of Conservation and Development 



Raleigh 
1951 



MEMBERS OF THE BOARD OF CONSERVATION 
AND DEVELOPMENT 

Governor W. Kerr Scott, Honorary Chairman Raleigh 

Miles J. Smith, Chairman Salisbury 

Walter J. Damtoft, Vice Chairman Canton 

Chas. S. Allen .. .. * Durham 

W. B. Austin Jefferson 

Oscar P. Breece Fayetteville 

Aubrey L. Cavenaugh .. r____:i Warsaw 

Staley A. Cook .. Burlington 

Ferd Davis _... Zebulon 

C. Sylvester Green -Chapel Hill 

Fred P. Latham Belhaven 

Mrs. Roland McClamroch Chapel Hill 

J. C. Murdock Troutmans 

W. Locke Robinson Mars Hill 

Eric W. Rodgers Scotland Neck 

George R. Ross, Director 



11 



LETTER OF TRANSMITTAL 



Raleigh, North Carolina 
April 25, 1951 

To His Excellency, Honorable W. Kerr Scott 
Governor of North Carolina 

Sir: 

I have the honor to submit herewith manuscript for publica- 
tion as Bulletin 62, "Feldspar Deposits of the Bryson City Dis- 
trict, North Carolina." This Bulletin is another in the series being 
made possible by the cooperation of the United States Geological 
Survey. 

Feldspar is one of the most important minerals being pro- 
duced in North Carolina. This report is the first detailed study 
of a feldspar district in North Carolina. It is believed that the 
information contained herein will be of considerable value to 
those interested in feldspar and feldspar production. 

Respectfully submitted, 

George R. Ross, 
Director. 



in 



CONTENTS 

Page 

Abstract 1 

Introduction 2 

General statement 2 

Previous Investigations 2 

Nature and extent of investigation 3 

Acknowledgments 3 

History of Mining 4 

General description of the Bryson City district 5 

Location and general information 5 

Topography and physiography 5 

Bedrock units 7 

General statement 7 

Metasedimentary rocks 8 

Metaperidotite , 9 

Hornblende and biotite schists and gneisses 9 

Metagabbro 10 

Granitic rocks 10 

General statement 10 

Granitic gneisses 10 

Mixed rocks 1 1 

Border gneiss .. « 1 1 

Other granitic rocks 11 

Structure 12 

General statement 12 

Structure of the metasedimentary rocks 13 

General features 1 3 

Minor folds 1 3 

Ma j or folds 1 5 

Faults 15 

Structure of the granitic complex 1 17 

General features 17 

Foliation and lineation 17 

Minor folds 17 

Heterogeneity of the complex 18 

Form of the granitic rocks and relations to 

metasedimentary rocks 19 

Nature of the rocks originally occupying the area 

of the granitic complex 22 

Pegmatites 22 

General statement 22 

Distribution and occurrence 23 

Size, shape, and attitude 23 

Structural relationships to enclosing rocks 24 

Internal structure 24 

General statement 24 

Zones 27 

Sequence of mineral assemblages in the zoned pegmatites 33 

Fracture-fillings 35 

Replacement bodies 36 

iv 



CONTENTS — CONTINUED 

Page 

Wall-rock alteration 36 

Mineralogy 37 

General statement 37 

Feldspars 37 

Quartz '_ 38 

Biotite 38 

Miscovite 39 

Distribution of biotite and muscovite 39 

Other minerals 40 

Origin of the pegmatites 41 

General statement 41 

Mode of emplacement 41 

Sequence of mineral formation 42 

Mineral deposits 43 

Feldspar deposits 43 

General statement 43 

Kinds of feldspar 43 

Commercial grades of feldspar 44 

Mining and preparation for market 45 

Types of feldspar deposits . 45 

Recommendations for feldspar prospecting 46 

Mica deposits 47 

General statement 47 

Characteristics of muscovite 48 

Preparation of muscovite for market 48 

Uses of mica 48 

Mica from deposits of the Bryson City district 49 

Occurrence of muscovite 49 

Kaolin deposits 49 

General statement 49 

Occurrence of kaolin 50 

Outlook for the future 50 

Descriptions of mines and prospects 51 

Morris prospect 51 

Carson mines 5 1 

General information 51 

General description of the pegmatite bodies 52 

North pegmatite 52 

South pegmatite 55 

Woody No. 1 mine 56 

Description . 56 

Feldspar 59 

Woody No. 2 prospect , 60 

Woody No. 3 mine 60 

Woody No. 4 mine 61 

Randall mine 61 

No. 8 prospect 63 

Swain mine 63 

General information . 63 

Development 63 

Geological relations 65 

Composition and internal structure of the pegmatite.. 66 



CONTENTS — CONTINUED 

Page 

Harry Thomas mine 67 

Deep Creek No. 1 mine 69 

General information 69 

Workings 69 

Form and relationships of the pegmatite 69 

Other pegmatite bodies 73 

Composition and internal structure 73 

Quartz and quartz-feldspar veins : 76 

Feldspar . 76 

Kaolin 76 

Outlook for the future 77 

McCracken mines 77 

General information 77 

North pegmatite 78 

Middle pegmatite 79 

Pegmatite bodies in the No. 6 working 79 

Summary 79 

South McCracken prospect, by Alfred L. Bush 

and E.N. Cameron 79 

McCracken southeast prospect 82 

Cox No. 1 mine , 82 

General information 82 

Form and structural relations of the pegmatite 82 

Composition and internal structure of the pegmatite 83 

Kaolin 11 . 85 

Feldspar 85 

Cox No. 2 deposit, by Alfred L. Bush and E. N. Cameron 85 

Pegmatite on road to Cox mine 86 

Lackey mine 1 86 

Hyatt prospect No. 1 - 87 

Hyatt prospect No. 2 .... r1 11 87 

Branton mine 87 

Description . 87 

Feldspar 90 

Cochran prospect 90 

Feldspar 91 

Mason prospect 91 

Nichols prospect 92 

Ball No. 1 mine 93 

Hans mine 94 

Harrison T. Crisp prospect : 94 

Ogle mines 9 5 

DeHart mine - 95 

Kaolin . 99 

Feldspar , ; 99 

Payne and Sullivan mine — --—-^ ---,*,-— ~? ; j 99 

vi 



CONTENTS — CONTINUED 

FIGURES 

Figure Page 

1. Index map of Bryson City area 5 

2. Structural features of metasedimentary rocks 14 

A. Axial-plane foliation in interbedded quartz-mica schist (thin 
layers) and micaceous quartzite. South bank of the Tuckasegee 
River, roadcut at great bend of river west of granitic complex. 

B. Symmetrical crinkling in mica schist enclosing mica quartzite. 
Roadcut on north bank of the Tuckasegee River, west of granitic 
complex. 

C. Asymmetrical crinkling in mica schist layer enclosed in mica- 
ceous quartzite. Same locality as for A. 

D. Second-order fold involving micaceous quartzite and quartz- 
mica schist (crumpled). Roadcut on south side of the Tucka- 
segee River at highway bridge, east of granitic complex. 

E. Nearly recumbent fold of second order, involving micaceous 
quartzite (core of fold) and quartz-mica schist. Note relation 
of axial planes of crumples in schist to axial plane of fold. Road- 
cut on west side of Deep Creek, between Tom Branch and Indian 
Creek. 

F. Second-order folds in micaceous quartzite and quartz-mica 
schist. Roadcut on south side of the Tuckasegee River, between 
highway bridge and Kirkland Creek. 

3. Structural features of granitic rocks 16 

A. Minor fold of interlayered biotite schist and granite gneiss. 
Railroad cut on west side of Buckner Branch, north of Messer 
Branch. 

B. Discordant foliation in granite gneiss and in an inclusion of bio- 
tite schist. Exposure along cut-off portion of old Highway 19, 
lower Cochran Branch. 

C. Discordant contact of granite with biotite schist. Roadcut on 
north side of the Tuckasegee River, west of Bryson Branch. All 
contacts of schist and granite are approximately perpendicular 
to the plane of the sketch. 

D. Contorted layers of granite gneiss in biotite schist. Lower layer 
partly dismembered. Upper adit, south McCracken mine. 

E. Detailed sketch of exposures on Highway 19, east of the bridge 
over Alarka Creek, showing an intermediate stage of granitiza- 
tion of biotite or biotite-hornblende schist. There are no true 
contacts in the exposure ; all boundaries are gradational. 

4. Idealized diagram to show types of pegmatite units 25 

5. Shapes and arrangement of zones in certain pegmatites of the Bry- 

son City district 26 

6. Sketch of small pegmatite body, McCracken No. 6 working 27 

7. Plan of the pegmatite body at the Cox No. 1 mine. Geology partly 

restored 28 

8. Plan of Deep Creek No. 1 pegmatite at elevation 2,150 feet 29 

9. Sketch showing development of zones around inclusions in the mid- 

dle intermediate zone, Carson south pegmatite 30 

10. Two stages in the exposure of a pegmatite by erosion. In the first 

stage the intermediate zone appears to be the core______ 30 

11. Isometric plate diagram showing arrangement of zones in the Deep 

Creek No. 1 pegmatite ■ 32 

vii 



CONTENTS CONTINUED 

Figure Page 

12. Sequence of mineral development in pegmatites of the Bryson City 

district 41 

13. Sketch map of workings at the Mason prospect and geologic plan 

of lower workings 91 

Table 

1. Sequence of mineral assemblages in 26 pegmatites of the Bryson 

City district 34 

2. Theoretical compositions of feldspar minerals 43 

Plates 

Plate 

1. Geologic map of the Bryson City area In pocket 

2. A. View looking northeast across the valley of Deep Creek from the 

terrace on the west side. The prominent terrace (center and 
right middle ground) is approximately at elevation 1,840 feet. 
The mouth of Betts Branch is at the extreme right. 

B. View northward along the axis of the topographic basin devel- 
oped on granitic rocks, from the 2,000-foot terrace immediately 
south of Bryson City (in fore and middle ground). 

C. Deep Creek No. 1 mine from the southeast 6 

3. A. Steeply dipping quartz fracture-fillings (to left of opening) 

cutting pegmatite at mouth of chamber, Carson mine, No. 3 
working. The most prominent fracture-filling is about 4 inches 
in maximum thickness. 
B. Cox No. 1 mine. Upper part of main working at left, beneath 
derrick boom 3 1 

4. Quartz core of Woody No. 4 pegmatite 33 

5. Carson mines, geologic map and plans of workings In pocket 

6. Carson mines, cross sections 53 

7. Woody No. 1 mine, geologic map, plans, and cross section 57 

8. Swain and Thomas mines, geologic map, plans, and cross 

section In pocket 

9. Swain mine, section along line A-A' 64 

10. Deep Creek No. 1 mine, geologic map and plan of main 

working In pocket 

11. Deep Creek No. 1 mine, plans of underground workings 68 

12. Deep Creek No. 1 mine, section along line A-A' 70 

13. Deep Creek No. 1 mine, section along line A-B-B' 71 

14. Deep Creek No. 1 mine, section along line C-C . 72 

15. McCracken mine, geologic map, plans, and cross sections In pocket 

16. South McCracken mine, geologic map, plan, and cross section 80 

17. Cox No. 1 and No. 2 mines, geologic map, plans, and cross 

sections In pocket 

18. Branton mine and Cochran prospect, geologic map, plans, and cross 

sections 88 

19. DeHart mine, geologic map, plans, and cross sections 96 

viii 



FELDSPAR DEPOSITS OF THE BRYSON CITY DISTRICT, NORTH CAROLINA 

By Eugene N. Cameron 

ABSTRACT 

Feldspar deposits developed in the Bryson City area of western North Carolina in the late 1930's and 
early 1940's are estimated to have yielded between 130,000 and 150,000 tons of feldspar, worth about $500,- 
000. With the decline of discoveries in the Spruce Pine district, the area attracted considerable interest as 
a source of new supplies of high-grade potash feldspar. The present investigation was undertaken to de- 
termine the size and extent of the feldspar deposits, the characteristics of the pegmatite bodies, and the rela- 
tion of the pegmatites to the structure and to the other rock units of the area. A further aim was to test 
the applicability of the zonal concept of pegmatite structure to prospecting and development of feldspar de- 
posits. 

The geologic history of the area apparently began with deposition of a series of interbedded sandy 
shales, feldspathic sandstones, and minor arkosic conglomerates, generally referred to the Ocoee series. 
These rocks were intruded by bodies of peridotite, gabbro, and perhaps other basic rocks. The whole series 
was then sharply folded along northeast-trending axes and metamorphosed to schists, quartzites, metacon- 
glomerates, metaperidotite, metagabbro, and hornblende and biotite schists and gneisses. Metamorphism was 
followed by a period of granitic invasion, during which a complex consisting partly of granite but largely of 
mixed rocks formed by soaking and granitization of the older rocks was developed. This granitic complex 
underlies an elliptical area about 7 miles long and 2 miles in maximum width. The internal structure of the 
complex suggests that it is an elongate lens, but its relation to the broader structure of the meta sedimentary 
rocks is not fully known. The metasedimentary rocks flank the granitic complex. The complex itself ap- 
pears to have developed largely by granitization of the metagabbro, metaperidotite, and the associated horn- 
blende and hornblende-biotite schists and gneisses. 

The main period of granitic invasion was followed by intrusion of dikes and irregular bodies of quartz 
monzonite porphyry, leucogranite, and granite porphyry. Deformation after intrusion of quartz monzonite 
porphyry produced a second foliation in parts of the older granitic rocks. Minor folds in the older gran- 
itic rocks and in the metasedimentary and metabasic rocks may have been produced at this stage, or may 
have developed during an intermediate stage of deformation. 

The final event in the development of the bedrock complex of the area was the emplacement of tabular, 
lenticular, pipelike, and irregular pegmatite bodies ranging up to more than 400 feet in length and more than 
100 feet in maximum width. These bodies are found within the granitic complex and in the metasediment- 
ary rocks adjacent to the complex. Bodies in granitic rocks were emplaced along fractures ; bodies in the 
metasedimentary rocks entered partly along fractures and partly along foliation surfaces. Most of the larger 
and more productive bodies occur along the northwest margin of the complex in a belt of border gneiss that 
extends from Deep Creek nearly to the Tuckasegee River. In part, the larger pegmatites appear to be re- 
lated to fractures that extend obliquely across the belt of border gneiss at places where the gneiss and the 
enclosing rocks are asymmetrically flexed. The intersections of fractures with the border gneiss appear to 
control the westward to southwestward plunges indicated for some of the pegmatite bodies. 

The pegmatites consist essentially of plagioclase, perthite, and quartz, with minor muscovite or biotite 
or both, accessory magnetite and garnet, and traces of tourmaline, allanite, and other minerals. Beryl is a 
prominent accessory mineral in part of one pegmatite. The pegmatites range from sensibly homogeneous 
to strikingly zoned. Most of them show two to six mappable zones, distinguished primarily on the basis of 
textural features and on proportions of quartz and feldspars. A definite sequence of mineral assemblages 
is recognizable in the pegmatites of the district, and this sequence is in essential agreement with sequences 
observed in other districts. Knowledge of this sequence has direct applications to problems of prospecting 
and development of feldspar deposits in the district. 

Both potash feldspar (perthite) and soda feldspar (probably albite to oligoclase) have been produced 
from the district. Feldspar of No. 1 grade comes from inner intermediate zones consisting of coarse to very 
coarse perthite and quartz, or of perthite, plagioclase, and quartz. No. 2 feldspar has been produced in 



2 Feldspar Deposits of the Bryson City District, North Carolina 

general from middle intermediate zones containing large proportions of feldspars in graphic intergrowth 
with quartz. The middle and inner intermediate zones lie in the interior parts of the pegmatites but are 
generally nearer the hanging wall than the f ootwall. In the two largest and most productive mines, perthite- 
quartz zones have been followed more than 360 feet down the plunge. 

Investigation of the district indicates that knowledge of the internal structure of the pegmatites, and of 
the relationship of the occurrence of commercial feldspar to zonal structure, can be effectively applied in 
prospecting and mining. Much time and effort have been spent in the district exploring parts of pegmatites 
unlikely to contain feldspar, and promising parts of pegmatites at some deposits have been overlooked. Rec- 
ommendations for prospecting procedures are made. 

Muscovite mica in books large enough to yield sheet mica has been found in a few pegmatites in the 
area, and small tonnages of mica appear to have been produced from time to time. Mica concentrations in 
the pegmatites, however, appear to be small, _#nd most of the books are so marred by structural defects that 
they are salable only as scrap mica. 

Descriptions of 29 pegmatite mines and prospects are given. The more important mines are discussed 
in detail, and detailed maps and other diagrams of the pegmatites exposed in them are presented. 

INTRODUCTION 

GENERAL STATEMENT 

Pegmatite deposits discovered in the early 1930's in the Bryson City district of western North Carolina 
have yielded appreciable quantities of high-grade potash feldspar, and in the middle 1940's the district at- 
tained second rank among the producing areas of the State. With the decline of discoveries in the Spruce 
Pine district, one hundred miles to the northeast, the Bryson City district aroused considerable interest as 
a possible source of new supplies of potash feldspar. 

In 1943, Charles E. Hunter, 1 assisted by W. T. McDaniels, Jr., examined the district to ascertain the 
mode of occurrence of the feldspar deposits. A reconnaissance geologic map of the granitic complex of 
Bryson City and its vicinity was made. The study indicated that the productive pegmatites occur mostly 
in a narrow belt along the western side of the granitic complex. In 1944 and 1945, Mr. Hunter discussed his 
findings with Dr. J. L. Stuckey, State Geologist, and with various members of the U. S. Geological Survey, 
and pointed out that more detailed study of the district was advisable. The present cooperative investiga- t 
tion is an outgrowth of these discussions. Its purpose was twofold — to make a thorough study of the geol- 
ogy and pegmatite deposits of the district, and to appraise the usefulness of the zonal concept of pegma- 
tite structure in prospecting, developing, and mining feldspar deposits. Full results of the investigation are. 
to be given later in a comprehensive report. The present report summarizes the more salient features of 
the geology and mineral deposits of the area. 

PREVIOUS INVESTIGATIONS 

The geological literature dealing directly with the Bryson City area is extremely scanty. Brief ref- 
erences to the region are found in the reports of the Geological Survey of North Carolina published in 
1875 2 and 1885. 3 On the geological map accompanying the second report, the rocks of the area are desig- 
nated as Huronian in age. The Tuckasegee drainage area also is mentioned briefly by Hayes and Campbell. 4 
Reports by Pratt 5 and Ries 6 contain brief references to kaolin mining in the Bryson City area and in ad- 
jacent parts of Swain County, and a corundum prospect southwest of Bryson City is mentioned by Pratt and 
Lewis. 7 In 1907 the geology of the Nantahala quadrangle, which adjoins the Bryson City area on the west 



1 Geologist, Regional Products Research Division, Tennessee Valley Authority. 

2 Kerr, W. C, Report of the Geological Survey of North Carolina, vol. I, Raleigh, 1875. 

3 Genth, F. A., and Kerr, W. C, Geology of North Carolina, vol. II, Raleigh, 1885. 

4 Hayes, C. W., and Campbell, M. R., Geomorphology of the southern Appalachians: Nat. Geog. Mag., vol. 6, pp. 63-126, 1894. 

5 Pratt, J. H., The mining industry in North Carolina: North Carolina Geologic and Economic Survey, Econ. Papers nos. 6 (1902), 
8 (1904), 9 (1905), 11 (1907), 14 (1907), 15 (1908), 23 (1911), 34 (1914), and 49 (1919). 

Ries, H., The clays of the United States east of the Mississippi River: U. S. Geol. Survey Prof. Paper 11, 298 pp., 1903. 
7 Pratt, J. H., and Lewis, J. V., Corundum and the peridotites of western North Carolina: North Carolina Geol. Survey, vol. 1, 
p. 47, p. 252, 1905. 



L 



Feldspar Deposits of the Bryson City District, North Carolina 3 

and southwest, was described by Arthur Keith. 8 As the Bryson City area lies on strike with the northeast- 
ern part of the Nantahala quadrangle, Keith's findings are of much interest. The geology of the Cowee quad- 
rangle, which includes the Bryson City area, also was mapped by Keith, and copies of his unpublished map 
have been available to the writer. 

In 1913, A. S. Watts 9 discussed the mining of kaolin and feldspar in western North Carolina, described 
three deposits in the Bryson City area, and gave test data for clays and "semikaolinized feldspar." In 1922 
and 1925, W. S. Bayley 10 described several of the kaolin deposits and discussed the kaolin industry of the 
time. 

Discussions of the broader features of the Appalachian region bear on certain problems of the Bryson 
City district. Of particular interest is a series of papers on the geomorphology of the southern Appalach- 
ians by Frank J. Wright. 11 Discussions of the stratigraphy and structure have been given by G. W. Stose 
and A. J. Stose. 12 

NATURE AND EXTENT OF INVESTIGATION 

Field work of the investigation occupied approximately six months of the period September 1946 
through April 1947. The principal pegmatite mines and prospects were studied and mapped in detail, and 
numerous smaller bodies were examined. An area at Bryson City of approximately 18 square miles un- 
derlain by the Bryson City granitic complex and enclosing rocks was then mapped on a scale of 1,000 feet 
to 1 inch. The base map used was an enlargement of the topographic map of the Bryson quadrangle, scale 
1 :24,000. Mapping consisted of systematic traverses at intervals of 500 to 1,000 feet, together with supple- 
mentary traverses to walk out contacts and other significant features. The principal pegmatite deposits 
were surveyed largely by plane table and telescopic alidade ; this was supplemented at the Deep Creek No. 1 
mine by transit survey. Surface exploration by means of postholes, pits, and trenches was done at several 
deposits. Mr. Alfred A. Bush assisted in the detailed mapping, supervised part of the exploratory work, 
and mapped and studied the South McCracken and Cox No. 2 deposits. 

ACKNOWLEDGMENTS 

The Bryson City area was studied in cooperation with the North Carolina Department of Conservation 
and Development, under an arrangement made with Dr. Jasper L. Stuckey, State Geologist. Information 
and assistance also were given freely by the Tennessee Valley Authority. The writer is particularly indebt- 
ed to Mr. Charles E. Hunter, geologist for TV A, and Mr. H. S. Rankin, Director of the Regional Products 
Research Division. The results of the reconnaissance study made in 1943 by Hunter and W. T. McDaniels, 
Jr., were made available to the writer and have been most helpful. Laborers and equipment provided by 
TVA made possible the exploratory work described below. Mr. R. H. Jahns has supplied the writer with a 
plane-table map of the surface workings of the Swain mine, made in June 1945. Mine owners and operators 
in the district have furnished much information and have extended full cooperation. The writer wishes to 
express his appreciation especially to Mr. W. J. Alexander and Mr. Oscar Pittman for information and for 
many courtesies. 

The classification and nomenclature of pegmatite units employed in this report follow the usage devel- 
oped by geologists of the U. S. Geological Survey during World War II, as elsewhere described. 13 

8 Keith, Arthur, U. S. Geol. Survey Atlas, Nantahala folio (no. 143), 1907. 

9 Watts, A. S., Mining and treatment of feldspar and kaolin in the southern Appalachian region: U. S. Bur. Mines Bull. 53, 170 
pp., 1913. 

10 Ries, H., Bayley, W. S., and others, High-grade clays of the eastern United States: U. S. Geol. Survey Bull. 708, 314 pp., 1922. 
Bayley, W. S., The kaolins of North Carolina: North Carolina Geol. Survey Bull. 29, 132 pp., 1925. 

11 Wright, F. J., The Blue Ridge of southern Virginia and western North Carolina: Denison univ., Sci. Lao., Jour., vol. 22, pp. 
116-132, 1927. 

, The erosional history of the Blue Ridge: Denison Univ., Sci. Lab., Jour., vol. 23, pp. 321-344, 1928. 

, The older Appalachians of the South: Denison Univ., Sci. Lab., Jour., vol. 26, pp. 143-250, 1931. 

, The newer Appalachians of the South, part 2, South of the New River: Denison Univ., Sci. Lab., Jour., vol. 31, 

pp. 93-142, 1936. 

— , Erosional history of the southern Appalachians: Jour. Geomorphology, vol. 5, no. 2, pp. 151-161, 1942. 

12 Stose, G. W., and Stose, A. J., The Chilhowee group and Ocoee series of the southern Appalachians: Amer. Jour. Sci., vol. 242, 
pp. 367-390, 401-416, 1944. 

, Ocoee, series of the southern Appalachians: Geol. Soc. America Bull., vol. 60, pp. 267-320, 1949. 

13 Cameron, E. N., Jahns, R. H., McNair, A. H., Page, L. R., The internal structure of granitic pegmatites: Econ. Geology, Mon. 2, 
113 pp., 1949. 



4 Feldspar Deposits of the Bryson City District, North Carolina 

The writer wishes to thank Mr. Carl E. Dutton for a critical reading of the manuscript and Mr. John 
B. Hanley for his careful editing. Mr. James J. Page and Mr. Preston E. Holtz have contributed helpful criti- 
cisms. 

HISTORY OF MINING 

Records of mining activity in the Bryson City area are scanty, and the mining history must be pieced 
together from fragmentary data from a number of sources. Judging from local reports, mining activity in 
the district began probably in the last century with production of small amounts of gold from the gravels 
of local streams such as Bryson Branch. In 1901 14 the first kaolin mines in Swain County (presumably 
north of Bryson City) were opened, and a small plant for cleaning and preparing the kaolin for market was 
erected. Pratt's reports for succeeding years 15 contain brief references to kaolin mining, together with 
some production data. Several companies were active at various times in the district during this period, 
but the operations of the Harris Clay Co. appear to have been the most productive. According to Mr. W. C. 
Queen and Mr. S. W. Enloe, the company began operations in 1907, or possibly a little earlier, and continued 
until 1912 or 1913. During this period about 16,000 tons of processed kaolin was shipped from mines of the 
company, and an additional 2,000 tons probably was received by the company from mines of other operators 
in the Bryson City district. The principal mine of the company was the Randall mine (pi. 1, no. 7). Clay 
dug from this mine was flumed down to a washing plant in the valley north of the Swain mine, thence to a 
drying and pressing plant on Deep Creek. The processed kaolin brought $13.50 per ton delivered to East 
Liverpool, Ohio. Freight was $4.37 per ton. Mr. Enloe estimates the total production of the Bryson City 
district at about 25,000 tons. Sporadic operations at other mines appear to have continued until the early 
1920's, but none of the mines appears to have yielded large amounts of clay. 

Accounts of kaolin mining and processing methods as practiced in western North Carolina around the 
turn of the century are given by H. Ries, 16 and the operations of a later period are described by A. S. Watts. 17 
Watts gives an analysis of finished clay from the Randall mine and of "semikaolinized feldspar." He noted 
the occurrence of fresh feldspar at the mine and suggested that "semikaolinized feldspar" (weathered per- 
thite) should be usable for pottery purposes. 

Nearly thirty years passed before the value of Watts' suggestion was demonstrated. According to local 
report, the first prospecting for feldspar in the Bryson City district was in 1934 by two brothers named 
Brooks. A few thousand tons of feldspar probably was produced, mostly from the Deep Creek No. 1 deposit, 
but sizable bodies of high-grade feldspar were not discovered. In 1939, W. J. Alexander leased the DeHart 
and Deep Creek No. 1 deposits. Production from the DeHart mine was small, though the product was No. 1 
feldspar of high quality. Prospecting at the Deep Creek No. 1 deposit, however, was shortly rewarded by 
the discovery of the shoot of feldspar which has proved to be the most important deposit of the district. 
Subsequent exploration of the pegmatite at the Swain mine led, in 1940, to discovery of another large shoot 
of high-grade feldspar. These discoveries attracted other operators to the district, and development of 
other deposits was the result. These efforts were not all crowned with success, but in early 1947 four mines 
were in operation and several other deposits were being prospected actively. 

Figures for total production of feldspar from the district are not available. The writer estimates that 
to the end of 1946 between 130,000 and 150,000 tons of crude feldspar, the major portion No. 1 potash feld- 
spar, was produced. The value of the output, at the mines, is estimated roughly at $500,000. 



14 Pratt, J. H., The mining industry in North Carolina: North Carolina Geol. and Econ. Survey, Econ Paper No. 6, p. 86, 1902. 

15 Pratt, J. H., The mining industry in North Carolina: North Carolina Geol. and Econ. Survey, Econ. Paper No. 8 (1904), No. 9 
(1905), No. 11 (1907), No. 14 (1907), No. 15 (1908), No. 23 (1911), No. 49 (1919). 

1B Ries, H., Clay deposits and clay industry in North Carolina: North Carolina Geol. Survey Bull. 13, 1897. 

, The clays of the United States east of the Mississippi River: U. S. Geol. Survey Prof. Paper 11, 298 pp., 1903. 

17 Watts, A. S., Mining and preparation of feldspar and kaolin in the southern Appalachian region: U. S. Bur. Mines Bull. 53, 170 

pp., 1913. 



Feldspar Deposits of the Bryson City District, North Carolina 5 

GENERAL DESCRIPTION OF THE BRYSON CITY DISTRICT 

LOCATION AND GENERAL INFORMATION 

The Bryson City district lies at the southern edge of the Great Smoky Mountains, 51 miles west-south- 
west of Asheville and about 42 miles northeast of Murphy (fig. 1). The Tuckasegee River flows through 
Bryson City and, on its westward course to junction with the Little Tennessee, nearly bisects the area. The 
area is served by the Murphy Branch of the Southern Railway. Paved roads connect it with Dillsboro and 
Waynesville to the east, and with Murphy, Franklin, and other communities to the south and southwest. 
Gravel and dirt roads give access to much of the surrounding territory. 



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Figure 1. Index Map of Bryson City Area 



Bryson City, a town of about 1,700 people, is the county seat of Swain County and the supply and 
community center for the surrounding area. The inhabitants depend for their livelihood chiefly on small 
industries, together with farming and lumbering carried on in the vicinity. The area is at the head' of 
Fontana Reservoir, and lying as it does in a setting of great beauty on the south edge of the Great Smoky 
Mountains National Park, it is becoming a center of a flourishing tourist trade. A small percentage of the 
residents have found employment in the feldspar mines. 



TOPOGRAPHY AND PHYSIOGRAPHY 

The area included in the Bryson quadrangle is mountainous. Elevations range from about 1,630 
feet at the point where the Tuckasegee River leaves the quadrangle to more than 4,000 feet on the high 
ridges of the northern and southeastern parts of the quadrangle. The town of Bryson City lies near the 
midpoint of a topographic basin developed on a granitic complex (pi. 1 and pi. 2, B). The basin is hilly but 
is markedly lower than the encircling ridges and appears subdued in contrast. Its basin-like character is 
best exhibited north of the Tuckasegee River, where Deep Creek, a brawling mountain torrent, and smaller 
streams to the west have cut deeply. The lower courses of these streams are marked by valleys in early to 
full maturity, with straths of various widths. The broadest and most continuous strath is along Deep 
Creek. 

The contrast between surrounding ridges and granite lowland was developed at a considerably earlier 
period, partly by the Tuckasegee River, partly by the tributary streams. An erosion surface was developed 
widely at this time on the granitic rocks north of the Tuckasegee River. The surface has since been ma- 
turely dissected, sediments mantling it have been eroded away, and probably the actual surface is nowhere 
preserved. Its former extent and approximate position, however, appear to be indicated by the summits of 



Feldspar Deposits of the Bryson City District, North Carolina 

Plate 2. 




A. View looking northeast across the valley of Deep Creek from the terrace on the west side. The prominent terrace (center 
and right middle ground) is at approximately elevation 1,840 feet. The mouth of Betts Branch is at the extreme right. 




B. View northward along the axis of the topographic basin developed on granitic 
rocks, from the 2,000-foot terrace immediately south of Bryson City (in fore and 
middle ground). 



Deep Creek No. 1 mine 
from the southeast. 



the divides of the present drainage, which lie at elevations close to 2,000 feet. Allowing for later dissec- 
tion, these summits define a surface extending from the Tuckasegee River opposite benchmark 1749 (on the 
railroad), nearly due north to the confluence of Juney Whank Branch and Deep Creek. The margin of the 
surface can be traced from this point southwestward to the upper part of Bryson Branch, east of Sherrill 
Gap, whence it passes irregularly southeastward to Bryson City. The arcuate ridge extending eastward and 
southeastward from a point just south of Franklin Grove Church, and forming the rim of the valley of 
Bryson Branch just above its junction with the Tuckasegee River, appears to have stood above the surface 
and may have formed the north wall of a meander of the ancient valley of the Tuckasegee River. 

This erosion surface is poorly preserved north of the Tuckasegee River in the area west of Bryson 
Branch ; it probably did not extend far from the river. South of the river the surface was apparently not 
extensive, but it is clearly indicated in the area of Arlington Church and the Bryson City reservoir, and is 
probably represented by the tops of the dissected ridges west of lower Buckner Branch and between lower 
Buckner Branch and Cochran Branch. 

The erosion surface is probably to be correlated with the surface described by Willis 18 and by Haves 
and Campbell 19 from the Asheville region and later correlated by Wright 20 with the Harrisburg peneplain 



18 Willis, B., Round about Asheville, North Carolina: Nat. Geog. Mag., vol. 1, pp. 291-300, 1889. 

10 Hayes, C. W., and Campbell, M. R., Geomorphology of the southern Appalachians: Nat. Geog. Mag., vol. 6, pp. 63-126, 1894. 

20 Wright, F. J., The older Appalachians of the South: Denison Univ., Sci. Lab., Jour., vol. 26, p. 165, 1931. 



L 



Feldspar Deposits of the Bryson City District, North Carolina 7 

of the Appalachian Valley to the west. The valleys developed during this stage of erosion appear to be pre- 
served, not greatly modified, along the upper parts of some of the smaller tributary streams, such as the 
upper end of Toot Hollow Branch, and the middle and upper portions of Durham, Juney Whank, and Tom 
Branches. For the first three streams named, the contact of the granitic complex with surrounding rocks 
is a fall line marked by small steep gorges. Above them the valleys open out into the "hollows" that figure 
so prominently in Carolina mountain legend and are one of the delightful features of the region. During 
the long history of successive degradations of the mountains, hollows have repeatedly developed above belts 
of resistant rocks that have impeded successive entrenchments of the streams. 

Certain long spurs that extend, with slightly undulating summits, outward from the higher ridges sug- 
gest remnants of still higher and older local erosion surfaces. The ragged mass of ridges with crestlines 
at elevations in the neighborhood of 2,200 feet, lying between Betts Branch and Johnson Branch, is a con- 
spicuous example. Dissection at higher levels is far advanced; the outlines of these ancient surfaces are 
obscure. 

Below the 2,000-foot level, terraces and benches are found at various elevations down to the floors of 
the present valleys (pi. 2, A). Cappings of poorly sorted gravels and sands are preserved on many of them, 
and the locations of the more prominent deposits are roughly shown on plate 1. The outlines of the ter- 
races are commonly not clearcut. Along their outer margins, there has been much slumping of the adjacent 
valley walls, so that the terraces merge into the valley slopes. At their streamward margins they pass 
similarly into terraces at lower levels, into deposits mantling the present valley floors, or into material wash- 
ed downward and forming a heavy mantle over the valley sides. No attempt has been made, in the present 
investigation, to outline these deposits precisely or to distinguish between deposits at various levels. 

The features of the Tuckasegee drainage basin are mirrored, though indistinctly, in those of the drain- 
age of Alarka Creek, where terraces or remnants of erosion surfaces at several elevations are more or less 
clearly indicated. 

In general, the area is at present, one of steep slopes and active erosion. In places the rocks are deeply 
weathered for 100 feet or more downward from the surface, but the soil mantle is thin. Decomposed but 
undisturbed bedrock lies no more than 3 to 6 feet below the surfaces of many of the slopes. This condition 
is important to prospectors, for it means that in large parts of the area the character and extent of bed- 
rock units beneath the soil can be determined rapidly and cheaply by means of postholes, pits, and shallow 
trenches. 

Denudation in the area is accomplished chiefly by fluvial erosion, but creep and small-scale landsliding 
play an important role in feeding the branches of the streams. Almost every excavation or mine opening 
that penetrates the overburden and the decomposed bedrock shows one or more surfaces along which land- 
slip has taken place, and some of the mine workings show these surfaces in bewildering profusion. With 
brief experience, one soon realizes from surface features that slips have occurred at innumerable places in 
the area. Inevitably, slips are more conspicuous around mine openings and are particularly prominent on 
steep slopes, where removal of support by excavation has led to new slips or to renewed movement on old 
surfaces. Such slips are a common source of difficulty in shallow openings, and larger slips led to the clos- 
ing of one of the district's three most productive mines. 

The author is convinced that mass movements of soil and weathered bedrock are a major factor in the 
degradation of the region. Movements 21 are mostly creep, slump, and earthflow, but debris-avalanching 
may occur, especially adjacent to artificial or natural excavations. 

BEDROCK UNITS 

GENERAL STATEMENT 

The rocks of the Bryson City area (pi. 1) are a varied assemblage, the cumulative result of a long and 
complex history of sedimentation, intrusion, granitization, and successive deformations. Part of this his- 
tory is plainly shown ; part is obscure and is likely to remain so until the geology of the older Appalachians 
as a whole has been much more intensively studied than at present. The present paper is essentially a 
21 Sharpe, C. E. S., Landslides and related phenomena, Columbia University Press, 137 pp., 1938. 



8 Feldspar Deposits of the Bryson City District, North Carolina 

progress report covering the results of field investigations to date. More thorough analysis of the structural 
and petrologic problems of the district must await laboratory studies and a subsequent review of critical 
features in the field. 

The rocks of the area comprise schists, metagraywackes and quartzites, and metaconglomerates deriv- 
ed from sediments ; hornblende, hornblende-biotite, and biotite schists and gneisses ; metaperidotite and gran- 
ite gneisses; and later granites, porphyritic quartz monzonite, pegmatites, and quartz veins. The ages of 
these rocks are unknown. They have been variously assigned to the pre-Cambrian, to the Paleozoic, or to 
both, but the different attempts to correlate them with formations of known age serves chiefly to demonstrate 
deficiencies in current knowledge of the region. 

METASEDIMENTARY ROCKS 

Surrounding the granitic complex is a monotonous succession of interbedded schists, feldspathic mica- 
ceous quartzites, and feldspathic metaconglomerates that are evidently derived from a thick series of clastic 
sediments. Schists and quartzites are the predominant members ; the metaconglomerates are a minor comp- 
onent. The thickness of these rocks is unknown. They form part of the group of rocks known as the Ocoee 
series. 

The schists are fine-grained to coarse-grained evenly bedded quartz-mica schists and feldspathic schists 
that occur in beds ranging from a knife-edge to many feet in thickness. The predominant types are fine- 
to medium-grained rocks consisting of quartz and muscovite, subordinate to minor biotite, accessory garnet, 
and minor amounts of feldspar. Variants are biotite-quartz schist, kyanite-bearing schists, and rare stau- 
rolite-bearing schists. West of the area mapped, along the road leading past Rock Creek Church, graphitic 
schists and phyllites rich in kyanite are exposed. As noted by Ross, 22 in the roadcut on the south side of the 
Tuckasegee River east of Milksick Cove, sulfides are widely disseminated in small amounts though the schists 
as well as associated quartzites and metaconglomerate. Weathering of the sulfides has resulted in marked 
yellow and brownish discoloration of the rock. 

The quartzites are evenly bedded, gray to dark gray, fine- to medium-grained rocks consisting of quartz 
and feldspar with various amounts of biotite or muscovite, or both, accessory garnet, and locally kyanite. 
Beds range from a fraction of an inch to 6 feet or more in thickness ; most are less than 1 foot thick. Lenses 
of pseudo-diorite 23 are present locally in the quartzites, particularly west of the granitic complex. They 
range from a few inches to more than 6 feet in length and from an inch to a foot in thickness. 

The metaconglomerates are gray to dark-gray rocks consisting of prominent white pebbles of feldspar 
1/16 inch to 3/8 inch in diameter set in a matrix consisting of flattened and crushed quartz pebbles orig- 
inally of comparable size. More or less sandy material is invariably present, and with increase in the ratio 
of sandy material to pebbles these rocks grade into quartzites, with which they are interbedded. In the few 
exposures of metaglomerates found, crossbedding is not commonly discernible, but it is probably a common 
feature of the quartzite-conglomerate assemblages. 

In places along the margins of the granitic complex, these metasedimentary rocks have been injected 
and impregnated with coarse granitic and pegmatitic material. The effects are particularly prominent along 
the east side of the granitic complex and around the south end, and are well exposed in the highway cuts on 
Highway 19 eastward from the mouth of Kirkland Creek to the bridge over the Tuckasegee River. These 
injected rocks were mapped as "Carolina gneiss" by Keith, 24 but apart from the introduced material, they 
differ in no essential respect from the metasedimentary rocks. Metaconglomerates and lenses of pseudodio- 
rite are included in the series. It seems evident that the "Carolina gneiss" as recognized by Keith in the 
Bryson City area is a lithologic facies, not a stratigraphic unit. Similar conclusions were reached by Kesler 25 
for the rocks of the Gaffney-Kings Mountain area. The remainder of the metasedimentary rocks is shown 



-- Ross, C. S., Origin of copper deposits of the Ducktown type in the southern Appalachian region: U. S. Geol. Survey Prof. Paper 

179, pp. 102-103, 1935. 
23 Emmons, W. H., and Laney, F. B., Geology and ore deposits of the Ducktown mining district, Tennessee: U. S. Geol. Survey 

Prof. Paper 139, pp. 15, 20-21, 1926. 

Ross, C. S., op. cit., pp. 2-22. 
21 Keith, Arthur, Cowee quadrangle, unpublished map in flies of U. S. Geological Survey. 
25 Kesler, T. A., The tin-spodumene belt of the Carolinas: U. S. Geol. Survey Bull. 936-J, p. 252, 1942. 

, Correlation of some metamorphic rocks in the central Carolina piedmont: Geol. Soc. America Bull., vol. 55, pp. 

755-782, 1944. 



Feldspar Deposits of the Bryson City District, North Carolina 9 

on Keith's map largely as part of the Great Smoky conglomerate. Just west of the granitic complex, synclin- 
al belts of the Nantahala slate, considered by Keith to overlie the Great Smoky conglomerate, are shown on 
his map, and one of these belts falls within the area mapped during the present investigation. Presumbaly, 
this designation was applied to prominent schist members of the metasedimentary series. The writer has 
discovered no basis either for the synclinal structure indicated by Keith or for the distinction of a Nantahala 
slate within the mapped area. Attempts to define such a unit and to trace it along the strike met with no 
success. 

METAPERIDOTITE 

Metaperidotite is exposed in two narrow belts, both lying within the granitic complex near its contact 
with metasedimentary rocks. The longer belt extends along the western margin of the complex. From a 
point half a mile northwest of the highway bridge over Alarka Creek it can be traced almost without inter- 
ruption for 9,000 feet north-northeastward. Scattered outcrops are found northward of this point as far as 
the Deep Creek No. 1 mine at the head of Toot Hollow, but its continuity over this distance is uncertain, ow- 
ing to lack of exposures. The second belt lies just west of the westernmost tongue of metasedimentary rocks 
that projects northward into the south end of the granitic complex. 

Dunite composed largely of olivine with a little enstatite was reported by Pratt and Lewis 26 from a 
locality 3 miles a little south of west of Bryson City, with the statement that corundum is said to have been 
found there. Unaltered dunite has not been found by the writer. Outcrops commonly show massive to schis- 
tose, medium-grained to extremely coarse-grained rock consisting essentially of tremolite, anthophyllite, and 
chlorite. This rock grades through intermediate facies into hornblende schist, hornblende-biotite schist, and 
biotite schist. The changes appear related partly or entirely to the development of the granitic complex. The 
biotite schists are commonly interlayered with feldspathic schists, and in several places, by increase of feld- 
spar, the biotite schists pass into biotite granite gneiss. Stages in the conversion of metaperidotite to biotite 
granite gneiss are particularly well shown in the cut bank along the new gravel road at the Oscar Martin pros- 
pect (pi. 1, No. 36). 

The peridotite has been profoundly modified since its intrusion, and its original extent and relationships 
to adjacent rocks are much obscured. These matters are discussed briefly in a subsequent section. 

HORNBLENDE AND BIOTITE SCHISTS AND GNEISSES 

Fine-grained to coarse-grained, dark-green to black rocks characterized by hornblende or biotite, or 
both, occur throughout the granitic complex. They form layers, lenses, and streaks ranging from less than 
one inch to tens of feet in thickness and from a foot to 100 feet or more in length. The outlines of the larger 
bodies cannot be traced satisfactorily in the field, hence no attempt has been made to distinguish them on 
the areal map. They show a wide range of composition, having various amounts of quartz, epidote, plagio- 
clase and potash feldspars, and accessory garnet, sphene, apatite, and black iron oxides. Clinopyroxene is 
present in at least one sample collected. 

These rocks are of the lithologic types described from various quadrangles of the older Appalachians and 
the Piedmont by Keith as the Roan gneiss, but no unit, of this name is distinguished in the Bryson City 
area on Keith's unpublished map of the Cowee quadrangle. In the Bryson City area, two groups of these 
rocks have been roughly discriminated by the writer, according to their occurrence and associations. One 
group is derived by metamorphism and granitization of peridotite. A series consisting of metaperidotite, 
hornblende schist, biotite schist, biotite-rich gneiss, and biotite granite gneiss is clearly indicated by exposures 
in mine workings along the main peridotite belt and in roadcuts at the Oscar Martin prospect that intersect 
the shorter peridotite belt on the north side of Alarka Creek. The other group consists of hornblende, horn- 
blende-biotite, and biotite schists and gneisses that are found elsewhere in the area and are not associated 
with metaperidotite. Like the first group, they were extensively modified during development of the granit- 
ic complex, and transitions to biotite granite gneiss are found in numerous places. 

Lithologically the two groups are much alike ; whether the distinction made in the field is a valid one is 
questionable. Keith 27 states that in the Nantahala quadrangle altered dunites and peridotites break 

20 Pratt, J. H., and Lewis, J. V., Corundum and the peridotites of western North Carolina: North Carolina Geol. Survey, vol. 1, p. 
47, 1905. 



10 Feldspar Deposits of the Bryson City District, North Carolina 

through and across the structure of the Roan gneiss, and more recently J. B. Hadley 28 has stated that the 
peridotite at Buck Creek, N. C, is injected into the Roan gneiss. Furthermore, Keith's mapping indicates 
that most of the ultramafic bodies in the Nantahala quadrangle are intrusive into Roan gneiss. It seems en- 
tirely possible that hornblende and biotitic rocks of both derivations are represented in the Bryson City area. 
The Roan gneiss was considered by Keith 29 to be a series of metamorphosed igneous rocks, probably 
ranging in composition from diorite to gabbro. In the Bryson City area, the presence of metagabbro that 
appears to grade into hornblende and biotite schists and gneisses lends support to Keith's conclusion. The 
metagabbro, however, has not been seen in contact with other rocks in the Bryson City area; its original 
mode of occurrence is obscure. 

METAGABBRO 

An area about 1,000 feet long and probably 350 feet in maximum width, straddling the divide west of 
the lower end of Bryson Branch, is underlain by rocks ranging from massive biotice-hornblende metagabbro 
through biotite-hornblende gneiss to biotite schist and gneiss. The core of the mass is apparently composed 
of metagabbro, the margins of biotite-hornblende and biotite schist and gneisses. The metagabbro is a med- 
ium-grained, massive, black and white mottled rock consisting essentially of plagioclase and clinopyroxene 
partly replaced by hornblende, biotite, and microcline. Pyroxene is lacking in the schistose and gneissic 
facies. The float indicates that the mass is cut by thin stringers of pegmatite, and pegmatitic solutions may 
be responsible for part of the alteration. 

Contacts of the metagabbro body are concealed. Presumably its emplacement preceded the development 
of the granitic complex. 

GRANITIC ROCKS 

General statement. — The rock complex of the central part of the area mapped shows a range of litho- 
logic types which is altogether extraordinary, the more so because preliminary microscopic examination in- 
dicates that the predominant types fall within the rather narrow mineralogical range between granite and 
granodiorite. In part this complexity is due to the presence of intrusives of different ages, in part it is due 
to granitization of metaperidotite, hornblende and biotite schist and gneiss, and metasedimentary rocks of 
the Great Smoky formation, and in part it is due to later deformation and metamorphism of some of the 
rocks of the complex. Some of the facies of the granitic gneisses form bodies large enough to be mapped as 
separate units, but pending petrographic studies, the entire complex, apart from a border gneiss forming the 
margin of part of the complex, is shown on plate 1 as a single unit. 

Granitic gneisses. — The predominant rocks are fine- to coarse-grained, equigranular to markedly inequi- 
granular, leucocratic and mesocratic gneisses ranging in composition from granitic to granodioritic. Both 
foliated and linear gneisses are present; foliation and lineation range from indistinctly to strongly devel- 
oped in various facies. Essential minerals are microcline and microperthite, plagioclase (probably ranging 
from albite-oligoclase to andesine) , and quartz ,with subordinate or accessory biotite, muscovite, hornblende, 
and epidote. The proportions of these minerals vary within a wide range. Sphene, apatite, zircon, mag- 
netite, and garnet are common accessory minerals. Foliation is due to knife-edge elongate or irregular lam- 
inae of biotite as much as 3 inches by 6 inches in length ; to parallel arrangement of augen composed of 
microcline or of microcline, plagioclase, and quartz; to alternating layers of quartz-rich, feldspar-rich, bio- 
tite-rich, hornblende-rich, or epidote-rich rock, ranging in thickness from a knife-edge to a half inch or 
more ; to elongate streaks of parallel-oriented biotite flakes ; to discontinuous folia of mica flakes intergrown 
with feldspars and quartz; and to parallel disseminated flakes of biotite or muscovite, or both. Linear 
structures and combinations of platy and linear structures are widely developed. Elongate patches and flat 
thin lenses of biotite, parallel-oriented augen, and pencil structures developed by rotational shear are the 
principal types. In a few places, such as the roadcuts on Highway 19 southwest of the Bryson City limit 
and the cuts on the north bank of the Tuckasegee River 600 feet east of the 1,721-foot benchmark, massive 
or virtually massive biotite granite is present. 



- T Keith, Arthur, II. S. Geol. Survey Geol. Atlas, Nantahala folio (no. 143), p. 3, 1907. 

28 Hadley, J. B., Preliminary report on corundum deposits in the Buck Creek peridotite area, Clay County, North Carolina: U. S. 

Geol. Survey Bull. 948-E, p. 103, 1949. 
-■' Keith, Arthur, op. cit., p. 3, 1907. 



Feldspar Deposits of the Bryson City District, North Carolina 11 

In addition to small-scale foliation, larger-scale layering is visible in the majority of outcrops. This 
structure is due to alternation of layers of contrasting texture or composition, or both. The layers range 
from an inch to tens of feet in thickness. Some layers, perhaps the majority, are thin flat lenses, but within 
the limits of the average exposure the apparent structure is that of a layered pile of rocks. 

Mixed rocks. — Most large outcrops of the granitic gneisses show layers or lenses of material rich in bitf- 
tite or, less commonly, hornblende. These layers range from biotite-rich granitic gneiss to the biotite or bio- 
tite-hornblende schists discussed above. Gradations between the two extremes are exposed at a large number 
of places. Both simple concordant or discordant injection and diffuse feldspathization and attendant changes 
are involved (fig. 3, E, Ms. p. 52) . The endless repetition of such features observed in the course of map- 
ping the complex indicates clearly that mixed rocks formed from the biotite and hornblende schists and 
gneisses are an important component of the complex. Discrimination between the mixed rocks and granitic 
rocks intrusive in the generally accepted sense is one of the major problems of the area. 

Though mixed rocks constitute the predominant types, normal intrusive contacts between hornblende 
and biotite schists and gneisses and granitic rocks have been observed at a number of places. Certain bodies 
of schist and gneiss appear to occur as angular inclusions in granitic gneiss, which is in sharp discordant 
contact with them and is apparently chilled against them (fig. 3, C, Ms. p. 52). 

Border gneiss. — Mapping of the granitic complex has shown that it can be divided into facies, each of 
which is characterized by some predominant type or types of rocks. In plate 1, however, only one facies the 
border gneiss, is shown as a separate unit. In typical exposures the rock is a medium-gray, markedly fol- 
iated gneiss consisting of microcline or composite quartz-feldspar porphyroblasts and augen set in a medium- 
to coarse-grained matrix that consists essentially of biotite, quartz, and feldspar. The augen and porphyro- 
blasts range from Vs mc h to l 1 /^ inches in length. Most exposures show foliation due to parallel orientation 
of porphyroblasts or augen, to alternation of augen-rich and augen-poor or augen-f ree bands, to alternating 
biotite-rich and biotite-f ree thin lenses, or combinations of these features. All gradations between unaffect- 
ed porphyroblasts and augen are found; the augen are due to granulation, flattening, and elongation by 
shearing parallel to foliation. 

The border gneiss is shown on plate 1 as a unit separating the metasedimentary rocks from the granitic 
complex. From the vicinity of the Ball No. 1 mine it extends northward around the end of the granitic 
complex and thence southward along the eastern margin as far as Betts Branch. South of Betts Branch 
along the eastern margin, and south of the Tuckasegee River along the western margin, border gneiss does 
not form a mappable unit, though rocks of similiar lithologic character are indicated by float or exposures 
in a number of places. 

The thickness of rocks mapped as border gneiss ranges from 50 to more than 200 feet. The rock is not 
a homogeneous or sharply defined unit, however, even apart from the lithologic variations described above, 
for it appears to be interlayered everywhere with granite gneiss and biotite schist and in places with horn- 
blende-biotite schist, actinolite schist, and actinolite-chlorite schist. These rocks form concordant layers 
an inch to 10 feet or more thick. The contact of the unit with metasedimentary rocks is commonly marked 
by a 1- to 10-foot zone of feldspathized mica schists and micaceous quartzite, and adjacent to border gneiss the 
quartzites in places likewise show small augen. No true transition, however, between metasedimentary rocks 
and border gneiss has been found. Inward toward the granitic complex, interlayered granitic gneiss be- 
comes more abundant. The inner boundary of the border gneiss has been located from float over most of 
the area ; it is only a rough approximation. Exposures along the western margin of the complex, particularly 
between the Branton and Deep Creek No. 1 mines, suggest that the border gneiss has been produced by 
granitization of biotite and biotite-hornblende schists. In part these schists appear to have been developed 
by metamorphism of peridotite. 

Other granitic rocks. — The granitic gneisses are cut by small bodies of granitic rocks of several different 
types. Leucocratic granite and fine-grained granite form small dikes and stringers cutting granitic gneisses 
in road and railroad cuts along the north side of the valley of Alarka Creek, in roadcuts along the north side 
of the Tuckasegee River west of Bryson City, and elsewhere. Dikes of medium-gray granite porphyry are 
exposed, or indicated by float, at a number of places in the southeastern part of the area. They consist of 
sparsely distributed, tiny (1 to 2 mm) phenocrysts of sodic plagioclase set in a microcrystalline ground- 



12 Feldspar Deposits of the Bryson City District, North Carolina 

mass of quartz, plagioclase, orthoclase, and biotite in faint parallel arrangement (flow structure). The 
best exposed is a series of roughly parallel dikes 1 to 20 inches thick, cutting the granitic gneisses in the 
long railroad cut between Frisbee Branch and Robinson Gap Branch. The dikes strike about N. 40° E. and 
dip about 35° W. Their contacts with gneiss are sharp and uneven. 

In plate 1, a trail is shown joining the Jenkins Branch road about 2,775 feet S. 341/2° E. of Arlington 
Church. Beginning a short distance north of the junction, light-colored bodies of decomposed leucogranite 
gneiss are exposed in the roadcut at intervals for a distance of nearly 500 feet. The longest body is exposed 
for nearly 250 feet. It cuts irregularly across interbedded mica schists and feldspathic mica quartzites, the 
foliation and bedding of which have an apparent dip of 60° to 70° S. The foliation of the leucogranite gneiss 
is in the same direction, though in general a few degrees less steep in dip, and in general is markedly dis- 
cordant to the contacts of the body. The foliation of the leucogranite gneiss is evidently due to metamorph- 
ism after emplacement. Bodies of similar granite gneiss are exposed at intervals in the metasedimentary 
rocks along the eastern margin of the granitic complex as far south as the southern slope of the northwest 
shoulder of Barnes Mountain, where two bodies of the gneiss are indicated on the map. Contacts of these 
two bodies are nowhere exposed, and outlines of the bodies as shown on the map are probably rough approx- 
imations. None of the other bodies could be traced out. In all known occurrences the leucogranite gneiss 
appears to have foliation essentially the same in attitude as that of the enclosing metasedimentary rocks. 
Comparable rock within the granite complex has not been certainly identified. 

In the lower part of the valley of Cochran Branch, the granitic complex is cut by a series of irregular 
dikelike bodies of a porphyritic quartz monzonite. This rock is characterized by phenocrysts of microcline 
% inch to 2 inches long set in a medium-grained pepper-and-salt matrix. The rock consists essentially of 
microcline, plagioclase, quartz, and biotite. One irregular dike at least 25 or 30 feet thick, with northwest- 
erly strike and a probable moderate southwesterly dip, is exposed in the first railroad cut west of Cochran 
Branch. Another dike, about 18 feet thick, is exposed along Highway 19, about 400 feet S. 55° W. of the 
intersection of the highway with the Bryson City limit. It is nearly vertical, trends roughly east, and cuts 
unevenly across granite gneiss, the foliation of which strikes N. 34° E. and dips 72°-77° SE. Both bodies 
contain inclusions of granitic gneiss and show distinct fluidal arrangement of thick tabular microcline pheno- 
crysts parallel to the dike margins. 

Another dikelike body of similar rock is exposed in the highway cut straddling the Bryson City limit, 
at the sign marking the limit. It is about 15 feet thick at the base of the cut but broadens upward. Its walls 
are uneven; its strike is probably about N. 5° W. and its dip steep east. It differs from the dikes described 
above in that it has a strong foliation striking N. 65° E. and dipping 66° SE. parellel to, and passing without 
interruption into, the foliation of the enclosing granite gneiss. The gneiss here is a thinly platy augen 
gneiss ; it has been produced by deformation and metamorphism of the less distinctly foliated granite 
gneiss that forms the wall rock of the dikes of porphyritic quartz monzonite described above. Southward 
the trend of the zone of intense shearing, of which this exposure is a part, swings to N. 25° E. and passes 
eastward of the undeformed dike exposed in the roadcut to the south. A second deformed, highly irregular, 
foliated body of porphyritic quartz monzonite is exposed in the first roadcut north of the city limit. 

North of the Tuckasegee River a body of unmetamorphosed porphyritic quartz monzonite 800 feet S. 35° 
E. of the McCracken mine appears to be indicated by float, and a second, too deeply weathered to be identi- 
fied with certainty, may be represented in a roadcut 1,050 feet N. 32° W. of Franklin Grove Church. 

STRUCTURE 

GENERAL STATEMENT 

The structure of the rocks of the Bryson City area is complex. The area lies in the belt of folded rocks 
forming the older Appalachian Mountains, and its rocks bear witness to profound deformation, punctuated 
by various stages of development of the granitic complex and followed by the emplacement of bodies of 
pegmatite. The keys to this history, so far as they are available, lie in the structural characteristics of the 
metasedimentary rocks flanking the complex, in the internal structures of the granitic complex, and in the 
relationships of the granitic rocks to the metasedimentary rocks. 



Feldspar Deposits of the Bryson City District, North Carolina 13 

STRUCTURE OF THE METASEDIMENTARY ROCKS 

General features. — The series of sedimentary rocks originally present in the area has been strongly 
folded and metamorphosed to schists and quartzites of middle rank. Dips of foliation and bedding range 
from gentle to vertical but are steep over most of the area. From Alarka Creek northward along the west 
side of the granitic complex to Ogle Knob, the bedding and foliation at most places dip steeply east. North 
of Ogle Knob, dips of bedding and foliation are prevailingly steep northwest or west along the western side 
of the area, although steep easterly dips are found in some places. In general, strike and dip of bedding and 
strike of foliation in the metasedimentary rocks appear to be parallel to the contact of metasedimentary 
rocks and border gneiss along this side of the granitic complex. The bedding of the metasedimentary rocks 
nearest the contact with border gneiss swings around the north end of the granitic complex and apparently 
conforms in general to the boundary of the complex. Foliation in both border gneiss and granite gneiss ap- 
pears to show a conformable swing in trend. Taken alone, the pattern of foliation and bedding suggests 
that the north end of the granitic complex is a blunt arch that plunges northward beneath the metasedimen- 
tary rocks. 

Along the east side of the granitic complex, foliation and bedding almost everywhere dip northeast, east, 
or southeast, but vertical or steep westerly dips are found locally. The strike and dip of bedding and the 
strike of foliation are in general parallel to the trend of the easterly margin of the granitic complex. Out- 
crops are sparse and poor around the south end of the granitic complex, except around the westernmost of 
the three prongs in which the granitic complex terminates. This prong appears to be wedge-shaped, with 
a gentle or moderate southward plunge, hence its structure is in marked contrast to the apparent domical 
form of the north end of the complex. This structural anomaly is one of the principal problems of the area. 
The available keys to the problem are in the smaller structural features of the metasedimentary rocks and 
the granitic rocks. The characteristics of the minor folds are particularly important. 

Minor folds. — Minor folds in the metasedimentary rocks range from gentle flexures to isoclinal folds, 
and their axial planes range from upright to recumbent. Two groups of folds are indicated by the relation- 
ships of bedding to foliation. One group consists of folds of the classical type in which the foliation is paral- 
lel or subparallel to the axial planes of the folds (fig. 2, A). In this report, folds of this group are termed 
first-order folds, because they represent the first stage of deformation recognizable in the area. As many 
of the first-order folds are isoclinal or nearly so, foliation in much of the area is parallel or nearly parallel 
to bedding. Divergencies of 5° to 20° in strike and of a few degrees to 90° in dip of foliation and bedding 
are shown in some exposures (fig. 2, B.), but over considerable portions of the area divergence is lacking or 
is so small that it has eluded a careful search of available exposures. Relationships of bedding and folia- 
tion .to first-order folds are best exposed west of Bryson City in the roadcuts on the west side of the Tucka- 
segee River, beginning where the river makes a great bend to the north. Here, interbedded schists and 
micaceous quartzites are involved in a series of first-order folds. Axial-plane schistosity is well developed 
in the schist layers. A few of the quartzite layers show a complementary fracture cleavage. 

The second group of minor folds is due to a second stage of deformation during which the limbs of the 
first-order folds were flexed, apparently under the influence of forces acting essentially in the same direction 
as before. The character of the resulting folds, here designated second-order folds, is shown in figure 2. 
The structures developed in the metasedimentary rocks are a function of the relative competencies of the 
beds. The quartzite beds yielded by simple flexure (fig. 2, D, E, F,), and the earlier developed foliation in 
these beds wraps around the crests and troughs of the newly developed folds. The schist layers yielded by 
intense crumpling of foliation (fig. 2, B, C, D, E) along axes that in general are systematically related to the 
crests and troughs of the new folds but have been influenced locally by the attitude of the previously devel- 
oped foliation. In such places, most of the adjustment of the beds during the second deformation appears to 
have been accomplished along the original foliation, and axes of crumples in schist layers commonly lie in 
the plane of the foliation. In second-order folds that have axes parallel to the intersections of bedding and 
foliation planes, the axes of crumples in schist are parallel to the axes of second-order folding of adjacent 
competent beds. Where fold axes and intersections diverge, the axes of crumples in schist and the axes of 
second-order folding in competent beds diverge. In all second-order folds, in sections perpendicular to the 
fold axes, the axial planes of the crumples are parallel or subparallel to the axial planes of the folds of the 



14 



Feldspar Deposits of the Bryson City District, North Carolina 



competent layers. The crumples are fractured along the axial planes where deformation was most intense, 
and locally false cleavage is strikingly developed. Recrystallization appears to have played little part in the 
development of this structure in the Bryson City area. 

Minor folds are distinguished from crumples in the discussion above, because the contrast between folds 
and crumples is striking in sections that consist of alternating layers of schist and quartzite, rocks that differ 
markedly in competence. The distinction is actually osne of scale ; every gradation between minute crumples 
and folds with amplitudes of 15 feet or more is exhibited in the area. 



5£ Quartz- 



es tj 




Micaceous 1 
quartzite^ ''i)ffVNI\ 



10 Feet 



SCALE 




W 



Ml 



lis 



SCALED 




Micaceous 
quartzite 




10 Feet 



SCALE 



Fractures 
NW \\ SE 




Mica schist 



Mica quartzite< 

I 2 Feet 
SCALE 



Quartz-mica schist 



SCALE 




Micaceous quartzite 
N65 ° E Overburden- 1 S.65°W 




Micaceous, 
quartzite 



SCALE 



Figure 2. Structural Features of Metasedimentary Rocks. 



A. Axial plane foliation in interbedded quartz-mica schist (thin layers) and micaceous quartzite. South bank of the Tukasegee 
River, roadcut at great bend of river west of granitic complex. 

B. Symmetrical crinkling in mica schist enclosing mica quartzite. Roadcut on north bank of the Tuckasegee River, west of gran- 
itic complex. 

C Asymmetrical crinkling in mica schist layer enclosed in micaceous quartzite. Same locality as for A. 

D. Second order fold involving micaceous quartzite and quartz-mica schist (crumpled). Roadcut on south side of the Tucka- 
segee River at highway bridge, east of granitic complex. 

E. Nearly recumbent fold of second order, involving micaceous quartzite (core of fold) and quartz-mica schist. Note relation of 
axial planes of crumples in schist to axial plane of fold. Roadcut on west side of Deep Creek, between Tom Branch and Indian 
Creek. 

F. Second-order folds in micaceous quartzite and quartz-mica schist. Roadcut on south side of the Tuckasegee River, between 
highway bridge and Kirkland Creek. 



Feldspar Deposits of the Bryson City District, North Carolina 15 

Second-order folds and crumples are widely developed in the area. They are particularly well displayed 
in the roadcuts along Highway 19 from the eastern margin of the granitic complex to the edge of the area 
mapped, and beyond it to the bridge over the Tuckasegee River. Their relationships to the first-order folds 
are best shown, however, in the roadcuts west of Bryson City referred to above. Second-order folds range 
from slight monoclinal bends to isoclinal folds. Most of the second-order folds have axial planes that dip 
eastward or southeastward at gentle to moderately steep angles; roadcuts on Deep Creek north of the end 
of the granitic complex show a series of recumbent isoclinal folds. 

Major folds. — The extent and character of the larger folds of the area are only partly known. The only 
large fold clearly recognizable is outside the area mapped; it is exposed west of the area in the roadcuts 
extending southward along the west bank of the Tuckasegee River from the mouth of Laurel Branch. Here 
the metasedimentary rocks are folded into an open, nearly upright anticline and complementary syncline, 
the syncline lying to the southeast. The foliation of schistose beds dips 55° to 70° E. Asymmetric crumpling 
is developed on the west limb of the anticline ; the axial planes of the crumples dip eastward. 

Stratigraphic tops and bottoms of beds as indicated by the relation of axial planes of crumples to the 
bedding agree with tops and bottoms of beds as indicated by the relation foliation to bedding. Except for the 
few places where the crests of first-order minor folds are exposed, this is the only locality in the area where 
the applicability of this method of analysis of folded structure to the Bryson City area can be tested. If these 
same relationships are applied as a general key to the structure of the metasedimentary rocks, the results 
are consistent in general with other data; the one apparent anomaly lies in the structure of the northern 
end of the granitic complex. 

Along the west side of the granitic complex, the foliation in general dips eastward, whereas the bed- 
ding either dips westward, or dips eastward at a given locality at an angle that is steeper than the angle of dip 
of the foliation. The metasedimentary rocks therefore appear to lie on the west limb of an anticline, and this 
appears to be consistent with the major structure as indicated in the section along the west bank of the 
Tuckasegee River from Laurel Branch eastward to the great bend. Except at two places that are well west 
of the margin of the granitic complex, the axial planes of crumples in schist layers likewise dip east, gen- 
erally at moderate angles, and this fact suggests a similar structural position for the beds. Along the east 
side of the granitic complex, the dip of the beds is almost everywhere easterly, and the foliation is either 
sensibly parallel to bedding or dips east at a smaller angle than the bedding. Similarly, the axial planes 
of asymmetric crumples in schist everywhere dips eastward at angles smaller than those of the dip of the 
bedding. These observations suggest that the metasedimentary rocks east of the complex to the limit of 
mapping, and beyond it along the Tuckasegee River to the highway bridge 1 mile east of the the granitic com- 
plex, lie on the overturned west limb of an anticline. If the granitic complex is essentially a concordant lens, 
the metasedimentary rocks both east and west of the complex are part of the same limb of a single major 
fold. This interpretation is consistent with the apparent wedging out of the westernmost of the three 
prongs in which the granitic complex terminates to the south, but it is not in harmony with the apparent 
domical form of the north end of the granitic complex and the immediately adjacent metasedimentary rocks. 

Two features of the area limit the use of minor structures as clues to the major structure. Outcrops are 
poor over most of the area underlain by metasedimentary rocks. Exposures are virtually limited to rail- 
road cuts, roadcuts, and outcrops in the beds of certain streams. The only good section across the eastern 
margin of the complex is given by the roadcuts and railroad cuts along the Tuckasegee River. Here bed- 
ding and foliation are almost everywhere parallel, and at most places stratigraphic tops and bottoms of beds 
must be inferred from the relation of bedding to axial planes of crumples and second-order folds. Crum- 
ples and minor folds are not developed in all beds, and it is possible that axes of isoclinal folds lie between 
points at which these features are developed. Observations of the minor structures, therefore, are not a 
fully satisfactory guide to the large-scale structure of the metasedimentary rocks east of the granitic com- 
plex. The lack of marker horizons in the metasedimentary rocks is an additional serious difficulty. How- 
ever, the structural features of the granitic complex discussed below shed some additional light upon the 
problem. 

Faults. — So far as indicated by mapping, faults other than landslips are not a prominent feature of the 
area. In the roadcut along the west bank of the Tuckasegee River, 700 feet south of Laurel Branch, a shear 



16 



Feldspar Deposits of the Bryson City District, North Carolina 



zone 2 to 3 feet wide with an apparent dip of 30° SE. cuts the metasedimentary rocks. The displacement is 
unknown. Minor faulting is indicated at a few of the pegmatite deposits, but little can be determined either 
of the attitudes of the fault surfaces or of the nature of displacements. It should be noted, however, that 
neither the character of the rocks nor the extent of exposures in the area lends itself to the detection of 
faulting. 



Biotite schist 




Granitic gneiss 
2 4 Feet 



SCALE 



Biotite schist 



Platy granite gneiss 




12 3 4 5 Feet 

I I I I I 1 

SCALE 



B 



ssw 






NNE 



,V/,VV. s ;£ f . Sandy gravel 
Massive to \> C } r Sr^ r ^l^^ 



Biotite schist- 



12 3 4 Feet 

I I I I I 

SCALE 



S.52°E 



N.52°W 




Biotite schist, in part with 
disseminated feldspar and 
thin granitic layers 

Granite gneiss 



X 



ngs 
biotite 



S.85°W 



N.85' 



Platy 

granite 

gneiss 



SCALE 



3 Feet 



D 




SCALE 



4 Feet 

_1 



Figure 3. Structural Features of Granitic Rock. 



A. Minor fold of interlayered biotite schist and granite gneiss. Railroad cut on west side of Buckner Branch, north of Messer 
Branch. 

B. Discordant foliation in granite gneiss and in an inclusion of biotite schist. Exposure along cut-off portion of old Highway 19, 
lower Cochran Branch. 

C. Discordant contact of granite with biotite schist. Roadcut on north side of the Tuckasegee River, west of Bryson Branch. All 
contacts of schist and granite are approximately perpendicular to the plane of the sketch. 

D. Contorted layers of granite gneiss in biotite schist. Lower layer partly dismembered. Upper adit, South McCracken mine. 

E. Detailed sketch of exposure on Highway 19, east of the bridge over Alarka Creek, showing an intermediate stage of granitiza- 
tion of biotite or biotite-hornblende schist. There are no true contacts in the exposure; all boundaries are gradational. 



Feldspar Deposits of the Bryson City District, North Carolina 17 

STRUCTURE OF THE GRANITIC COMPLEX 

General features. — Like the metasedimentary rocks, the granitic complex bears evidence of a compli- 
cated history, which is recorded in a considerable range of structural features. The more important features 
are: (1) foliation and lineation in the complex and the relation of these features to the boundaries of the 
complex and to various rock types within it; (2) minor folds within the complex; (3) the heterogeneity of 
the complex; and (4) the form of the complex and its relationships to the metasedimentary rocks. 

Foliation and lineation. — Two types of foliation are present in the rocks of the granitic complex. The 
first and more characteristic is expressed by layering, parallel discoid or elongate lenses, parallel folia of 
contrasting composition or texture, or parallel arrangement of mineral grains. This type of foliation ranges 
from faint to extremely marked. It is widely developed and is everywhere conformable with the foliation 
of the adjacent border gneiss or metasedimentary rocks, and with the boundary of the granitic complex. 
In places the foliation is accompanied by lineation, which is commonly expressed by elongate mineral grains 
or groups of grains within foliation surfaces. In most outcrops the direction of plunge of lineation is difficult 
to measure accurately ; it is more widely developed than suggested by the data given on the map. 

The second type of foliation, where recognizable, is superimposed upon the first and is produced by de- 
formation subsequent to the development of the main body of granitic gneisses. The relationships are clear- 
ly shown in roadcuts on Highway 19, at the point where the road crosses the Bryson City limit in the valley 
of Cochran Branch. Four hundred feet S. 55° W. of the intersection of the highway with the city limit, gran- 
ite gneiss with faint to distinct foliation striking N. 34° E. and dipping 72° to 77° SE. is cut by an unmeta- 
morphosed dike of porphyritic quartz monzonite. The dike trends roughly east and is nearly vertical. At 
the city limit the granite gneiss is cut by a similar dike, but here both dike and granite gneiss have a mark- 
ed thinly platy foliation that strikes N. 65° E., and the zone of superimposed foliation swings behind (east 
of) the cuts showing the unfoliated dike. These exposures show that the foliation of the rocks of the granitic 
complex was developed in part after the intrusion of the quartzite monzonite porphyry. Figure 3 B shows dis- 
cordant foliation in granite gneiss and biotite schist in the same belt as the foliated quartz monzonite 
porphyry. Foliation in schists and granite gneiss is normally parallel. Criteria for distinguishing earlier 
from later foliation throughout the complex have not been developed. However, the presence of unfoliated 
quartz monzonite dikes at several places in the complex suggests that the later foliation has been developed 
only in certain belts within the complex. The author's impression is that foliation in most of the complex is 
of the earlier type. 

On the north side of the Tuckasegee River, muscovite granite gneiss is exposed in the railroad cut west 
of the northward-projecting wedge of metasedimentary rocks. In places the gneiss shows an unusual struc- 
ture that appears to be a variant of the common type of foliation. The rock here consists of steeply dipping 
alternating layers of highly schistose and indistinctly schistore muscovite granite gneiss. The layered struc- 
ture strikes N. 3°W. and dips 66° E. The foliation has the same strike but dips 57° E. The origin of this 
structure is uncertain ; it probably represents a structure inherited from metasedimentary rocks that have 
been granitized. 

Minor folds. — Minor folds are numerous in the granitic complex. In form they closely resemble the 
second-order folds in the metasedimentary rocks; they are markedly asymmetric, with their long limbs 
subparellel to the regional dip of foliation. The folds are strikingly developed between Messer Branch and 
the Tuckasegee River, in places southeast and east of Bryson City, and in places north of the Tuckasegee 
River and west of Deep Creek. The attitudes of these folds can be measured accurately in very few out- 
crops, but their general pattern has been studied in some detail. The folds are registered in flexure of the 
foliation. Viewed in vertical section most of the folds indicate an upward movement of the rocks on the 
west, relative to the rocks on the east. This fact is in agreement with the pattern of second-order folds in 
metasedimentary rocks to the east and west of the complex. Most of the known exceptions lie in a narrow 
belt extending west of Buckner Branch from Gibby Branch to the Tuckasegee River, where the relationship 
is reversed. However, the normal pattern is found again in the outcrops of granite gneiss nearest the west- 
ern boundary of the complex. The relationships suggest a sizable second-order fold within the granitic 
complex between Buckner Branch and the west margin of the complex. 



18 Feldspar Deposits of the Bryson City District, North Carolina 

Exposures in the long roadcut extending eastward from the business section of Bryson City on Highway 

19 indicate that there is a definite relationship between the minor folds within the granitic complex and 
the second-order folds in the metasedimentary rocks. The complex here includes a series of layers or en- 
closures of biotite schist. At a point about 900 feet from the west end of the cut, biotite schist is crumpled 
along axes that plunge 21° — N. 22° E. The axial planes of the crumples dip approximately 20° S.E., whereas 
the over-all dip of layering and foliation in the schists is 84° NW. The pattern of these crumples is the same 
as that of the second-order folds in sedimentary rocks east of the complex and is duplicated by the pattern 
of minor folds in granite gneisses in the same roadcut. It appears evident that minor folding in the granite 
was developed in the second stage of regional deformation. The same conclusion is suggested by relation- 
ships in several mine tunnels along the western margin of the complex, where thin layers of granite gneiss 
alternate with biotite schists (fig. 3, D). The emplacement of the granite gneiss has clearly been controlled 
by the foliation of the biotite schists, but the layers have been deformed and locally disrupted during crumpl- 
ing of the biotite schists. 

An exposure in the first roadcut east of the business section of Bryson City illustrates a type of linear 
structure that is strikingly developed in some of the granitic gneisses east and southeast of the business sec- 
tion. This structure consists of spindles of quartz and feldspar up to 6 inches long and half an inch in 
diameter, wrapped in elongate biotite folia. The linear structure thus developed plunges parallel to the 
axes of the crumples in the biotite schist layers, and is evidently due to the same deformation. 

Heterogeneity of the granitic complex. — The origin of the heterogeneity of the granitic complex is inti- 
mately related to the origin of the foliation, and no explanation of the one is satisfactory that does not also 
account for the other. The key to heterogeneity appears to be largely in the character and relationships of 
inclusions within the complex. Inclusions of fine-grained quartz-biotite and quartz-biotite-feldspar schist, 
and of coarse-grained biotite schist or biotite-hornblende schist are very abundant. Many of them exposed 
in the area south of Franklin Grove Church and west of lower Bryson Branch, and in the lower valley of 
Cochran Branch, have the relationships of ordinary xenoliths in an intrusive granite. Contacts with granite 
in places truncate the foliation of the schists (fig. 3, C) . The granite against the inclusions is relatively fine 
grained and massive and shows faint foliation parallel to the contacts. Other enclosures consist of layers of 
dark schists alternating with layers of granite gneiss ; the foliation in both types of rocks is parallel to the 
layering. Contacts range from sharp to fading and indistinct, and some layers show gradations from schists 
to granite gneiss. Complex shattering, injection, and feldspathization of the dark schists is shown (fig. 3, E) 
in still other exposures. These effects are exhibited in hundreds of places in the complex in one stage or 
another. Along the eastern side of the complex, there has been extensive development of mixed rocks from 
metasedimentary rocks, especially in the area from Betts Branch to Jenkins Branch, and the rocks Keith 
mapped here as Carolina gneiss consist of metasedimentary rocks that have been partly granitized. Expos- 
ures along the margins of the belts of metaperidotite indicate that this rock likewise has been partly gran- 
itized. The development of mixed rocks is indicated at so many places that it seems clear that such rocks 
form the major part of the granitic complex. The uneven operation of the process of granitization offers 
the only reasonable explanation for the extraordinary large- and small-scale inhomogeneity exhibited by the 
granitic rocks, for the presence of innumerable oriented inclusions and partings of dark schists and meta- 
sedimentary rocks in the complex, and for the lack of any systematic relation of various facies of granitic 
rocks, the border gneiss excepted, to the borders of the complex. Furthermore, various exposures indicate 
that the granitic complex was formed after the development of schistosity in the metasedimentary rocks, 
for feldspathization of biotite schists and metasedimentary rocks was controlled by foliation. The granitic 
invasion took place, however, largely prior to the second stage of deformation that produced the second-order 
folds and crumples in metasedimentary rocks. During this stage minor folds also were widely developed in 
the granitic rocks (fig. 3, A). Thin layers of granite, developed in rocks marginal to the complex, were in 
places sharply folded and even disrupted, with local development of boudinage structure (fig. 3, D). In part, 
however, granitization appears to have been contemporaneous with the second stage of deformation, for 
lenses of massive granite similar to adjacent granite gneiss in composition and grading into it were develop- 
ed locally along fractures systematically related to minor folds. 

If uneven granitization is the major cause of inhomogeneity of the complex, the foliation of the granitic 
rocks is inherited in large measure from that of preexisting rocks. The origin of the foliation pattern with- 



Feldspar Deposits of the Bryson City District, North Carolina 19 

in and adjacent to the complex and the origin of the pattern of minor folds within the complex must then 
be sought largely in the same structural history that has produced foliation and minor folds in the metasedi- 
mentary rocks. Locally, a later foliation appears to have been produced by deformation after the intrusion 
of porphyritic quartz monzonite, but the over-all structural pattern within the granitic complex does not seem 
to have been modified greatly. 

Form of the granitic complex and relations to metasedimentary rocks. — In his description of the Nan- 
tahala quadrangle, Keith 30 states that the granites of the quadrangle are Archean in age and intrusive into 
the Carolina or Roan gneiss, and that an angular unconformity separates these older rocks from Cambrian 
metasedimentary rocks of the Great Smoky formation. On his manuscript maps of the Cowee quadrangle 
(unpublished), a belt of Carolina gneiss is shown extending northeastward from the east edge of the Nan- 
tahala quadrangle. The gneiss is shown as extending around the Bryson City granitic complex except at 
the north end, where granite is shown directly in contact with the Great Smoky formation. The Bryson City 
complex is shown correctly as separate from another comparable complex lying en echelon to the northeast. 
In 1944, Stose and Stose 31 published a map that includes the Bryson City area. No granite is shown in the 
position of the Bryson City complex, but a northeast-trending belt of intrusive granite about 20 miles long 
is shown southeast of Bryson City. The northwest boundary of the granite belt, as shown on their map, 
lies approximately at the actual southeast boundary of the Bryson City complex. They state (p. 411) : 
"Where seen by the writers north of Whittier, North Carolina, it is a muscovite-biotite granite which in- 
trudes, injects, and replaces rocks of the Ocoee series" (the metasedimentary rocks). They state further that 
the granite at Whittier is similar to Keith's Whiteside granite 32 and express their agreement with Keith's 
suggestion that this and other similar granites may be as late as Carboniferous in age. Stose and Stose were 
evidently not aware that the Bryson City and Whittier granitic complexes are separate, and were under a 
misapprehension as to the position of the Bryson City complex. In 1949, 33 the same authors stated that their 
more recent field work indicates that the granite gneiss is part of the injection complex exposed in an anti- 
cline in the Ocoee series and that the Hurricane graywacke (basal member of Ocoee series as described by 
them) stratigraphically overlies the granite gneiss. The "late Paleozoic granite" of the 1944 map is shown 
on their 1949 map as part of an "early pre-Cambrian granite and injection complex" extending from the 
Roan Mountain quadrangle 200 miles southwestward into Georgia. The observations leading to this revision 
are not recorded. 

The results of the present investigation require considerable revision of the conclusions of Keith and of 
Stose and Stose. In the Bryson City area, the rocks mapped by Keith as Carolina gneiss are a partly gran- 
itized f acies of the metasedimentary rocks. The granitic rocks of the area are younger than the metasedi- 
mentary rocks, but their relationship to the deformation of the sediments is far from simple. The cross- 
cutting bodies of light-colored granite gneiss in the metasedimentary rocks along the southeastern margin 
of the granitic complex may have been intruded prior to the development of the foliation of the metasedi- 
mentary rocks. The main body of granitic rocks was emplaced after foliation was developed in the meta- 
sedimentary rocks, in part prior to, in part contemporaneous with, the stage of deformation during which 
second-order folds were produced. The form of the granitic complex and its structural relationships to the 
metasedimentary rocks must be interpreted in terms of this history. 

If the metasedimentary rocks on both flanks of the complex are on the same limb of a single major fold, 
the west limb of a major anticline, then the granitic complex is essentially a lens. There is a good deal of 
evidence to support this interpretation. The structural evidence that the sedimentary rocks lie on the limb 
of a single major fold has already been cited. This evidence is in agreement with lack of any arch struc- 
ture in the foliation of the granitic rocks along the line of the Tuckasegee River, where the best section of 
the granitic complex is exposed. The structural features of the narrow wedge of metasedimentary rocks 
that crosses the Tuckasegee River east of Deep Creek offer further evidence. A long cut extending north- 
eastward from the railroad gives a complete section across this wedge. The rocks exposed in the cut are 
interbedded mica quartzites and partly granitized coarse-grained muscovite-biotite schists. Bedding and 



30 Keith, Arthur, U. S. Geol. Survey Geol. Atlas, Nantahala folio (no. 143), 1907. 

31 Stose, G. W., and Stose, A. J., The Chilhowee group and Ocoee series of the southern Appalachians: Am. Jour. Sci., vol. 242, p. 
372, 1944. 

32 Keith, Arthur, U. S. Geol. Survey Geol. Atlas, Pisgah folio (no. 147), p. 4, 1907. 

33 Stose, G. W., and Stose, A. J., Ocoee series of the southern Appalachians: Geol. Soc. America Bull., vol. 60, p. 274, 1949. 



20 Feldspar Deposits of the Bryson City District, North Carolina 

foliation are sensibly parallel, but second-order folds and crumples have developed in the rocks in the west- 
ern part of the wedge. The bedding there dips steeply east ; the folds are sharply asymmetric and have axial 
planes dipping gently east. Their relation to bedding suggests that the beds are on the overturned west limb 
of a major anticline, hence in the same structural position as the beds to the east and west of the complex. 
The contact with granite gneiss to the west is covered, but the two rocks are exposed within 10 feet of each 
other. In the eastern part of the wedge, bedding and foliation are sensibly parallel. It is possible that a 
synclinal axis passes somewhere through the middle of the cut. However, the minor structures of the meta- 
sedimentary rocks immediately east of the granite gneiss reentrant east of the wedge indicate that the meta- 
sedimentary rocks lie on the overturned west limb of a major anticline. If a synclinal axis passes through 
the wedge of metasedimentary rocks, an anticline and a complementary syncline are required in the reentrant 
of granite gneiss. There is no evidence of the existence of these two folds. Furthermore, if the wedge is 
synclinal, the pattern on the map requires a southward plunge, whereas the axes of minor folds in the wedge 
plunge N. 4° E. at an angle of about 13°. Inasmuch as exposures are poor in the reentrant of granitic gneiss 
east of the wedge, conclusive evidence of the structure is lacking, but the data at hand suggest that the re- 
entrant of granite gneiss is not related to folding. It appears to be merely a projection of the main body of 
granitic gneiss produced largely by uneven granitization of metasedimentary rocks. 

The structure of the south end of the granitic complex next requires consideration. Only the western 
prong merits critical discussion, because exposures of the middle and eastern of the three prongs in which 
the granitic complex terminates are almost wholly concealed. The western prong is bounded on the east 
by the wedge of schist that extends northward across Alarka Creek. A nearly complete section through this 
wedge is given by roadcuts and the new railroad cut north of the creek. Bedding and foliation in the meta- 
sedimentary rocks dip steeply eastward and are sensibly parallel throughout the wedge, but near the west- 
ern contact of the wedge the relation of crumples to bedding suggests that the beds are overturned to the 
west. The west contact of the wedge cuts across the sharp bend of Highway 19 west of the bridge and 
intersects it near the point at which the highway climbs the valley wall. The roadcuts give a nearly continu- 
ous series of exposures from this point to the junction of the highway with the Welch Branch road. South- 
ward the strike of the metasedimentary rocks swings from N. 35° E. to N. 56° E., and the dip decreases from 
52° SE. to 27°-35° SE. in the cut on Highway 19 just east of the junction with the Welch Branch road. In 
the western two-thirds of this cut the rocks structurally underlying the metasedimentary rocks of the east- 
ern part of the cut are mostly schists and gneisses characterized by numerous augen of feldspar. Cutting 
these rocks and interlayered with them are fine- to medium-grained leucocratic granite gneisses. Some of 
the augen-bearing rocks resemble the border gneiss found around the northern end of the granitic complex, 
but some resemble augen-bearing layers in the partly granitized sedimentary rocks east of the mouth of 
Welch Branch. The augen-bearing rocks and interlayered granitic gneisses extend upward and are ex- 
posed in the cuts along the Welch Branch road east of its junction with Highway 19. They are flanked and 
structurally overlain to the east by metasedimentary rocks, and at the junction of the two roads they are 
exposed conformably overlying typical interbedded schists and quartzites. Southwest of this point the 
strike of the foliation and bedding in metasedimentary rocks swings to east-northeast and finally to north, 
and the dip increases. The augen-bearing rocks do not appear in exposures along the strike south of the 
junction; presumably they wedge out. 

Bedding and foliation are parallel in most of the exposures of metasedimentary rocks on the east side 
of the prong, and crumpling is lacking. Asymmetric crumpling of schists is shown, however, at the point 
where the Welch Branch road turns south along the branch. Bedding dips 47° SE. at this point; the axial 
planes of the crumples dip 18° SE. The relationship suggests again that the metasedimentary rocks on the 
east side of the prong are overturned to the west. The beds on the west side of the prong are well exposed 
in the new railroad cut from the Davis Branch road to the boundary of the granitic complex. They show 
the same relationship as the beds east of the prong, hence the prong appears to be wedge-shaped, not dom- 
ical. As indicated on the map, however, exposures of the granitic gneiss proper at the apex of the wedge 
are not adequate to provide a check on the interpretation. Presumably the apex of the wedge plunges to 
the south. 

The evidence thus far presented appears to indicate that the granitic complex is an irregular lens. Cer- 
tain features of the north end of the complex, however, suggest that it has the form of a structural dome 



Feldspar Deposits of the Bryson City District, North Carolina 21 

plunging northward at a moderate angle. Although the border gneiss and granitic gneisses are poorly 
exposed in this part of the complex, it seems clear (1) that the border gneiss forms a continuous unit that 
passes completely around the north end, (2) that the border gneiss in general dips outward from the com- 
plex, and (3) that the foliation of the border gneiss, so far as indicated by surface exposures, also dips out- 
ward in general from the granitic complex. If the foliation of the border gneiss and granitic gneisses is an 
inherited structure, as the writer has concluded, then the domical structure cannot be ascribed to thrust of 
an intrusive body of granitic magma. The answer to the structural pattern must therefore be sought in 
terms of the development of the folded structure of the district, in the first-order folding or the second- 
order folding, or both. 

It is at once evident that the structural pattern cannot be ascribed to first-order folding, for the folia- 
tion of the border gneiss in the axial part of the domical structure is in general conformable with, not dis- 
cordant to, the crest of the dome. It is therefore not of the axial-plane type characteristic of first-order 
folds in the district. So far as is indicated by meager exposures, the same relation holds for the foliation of 
the granitic gneisses. The domical structure would therefore appear to be related in some way to the 
second-order folds in which the preexisting foliation has been folded, and therefore wraps around the crests 
and troughs of the folds. 

Some light on the problem is given by the structural features of the metasedimentary rocks at and near 
the crest of the dome, as indicated by exposures in the vicinity of Deep Creek. The most critical exposures 
appear to be along the creek between Tom Branch and the contact of metasedimentary rocks with border 
gneiss. This area has been examined with particular care. In most of the exposures bedding and foliation 
of the metasedimentary rocks are sensibly parallel; the beds are evidently the limbs of isoclinal folds, but 
crests and troughs of folds are commonly not discernible. The principal exceptions are a few exposures in 
roadcuts along the west side of Deep Creek. In the long cut that begins 875 feet northeast along the road 
from the contact, a series of recumbent folds with axes plunging approximately N. 85° W. is well exposed. 
The axial planes of the folds and the beds on the limbs dip northwest at moderate to gentle angles. Another 
set of folds in metasedimentary rocks near the contact with the border gneiss plunges northeast, parallel 
to the inferred crest of the granitic complex, and beds on the limbs dip in the same direction, in structural 
conformity with the foliation of the border gneiss. The metasedimentary rocks on the east side of Deep Creek 
appear homoclinal and dip northeast to east, but the outcrops are not of the kind in which gently or mod- 
erately plunging axes of isoclinal folds are likely to be detected. The data are limited, but they suggest that 
the apparent arch of metasedimentary rocks over the border gneiss is in reality an arch of axial planes of 
isoclinal and near-isoclinal second-order folds. 

If this interpretation is the correct one, the pattern of foliation in the border gneiss belt remains to be 
explained. There appear to be two hypotheses that might fit the facts so far as known. One is that under 
the conditions of second-order folding, the metasedimentary rocks were structurally incompetent. They were 
therefore mashed against the more competent lens of granitic rocks and adjusted themselves, by means of 
intricate isoclinal folding, to the form of the termination of the lens. In the process, the border gneiss and 
the outermost part of the granitic gneisses were intensely deformed and assumed a similar pattern. This 
hypothesis finds some support in exposures in an adit at the Morris prospect (pi. 1) in which interlay ered 
biotite schist and granitic gneiss are thrown into a series of intricate second-order folds. The second possibil- 
ity is that at its north end the lens of granitic rocks is involved in a large, northward-plunging second-order 
fold, of which it is the anticlinal member. The complementary syncline should be to the east. If this is the struc- 
ture, the points of emergence of the axes of both the anticline and the syncline should be found along the 
eastern margin of the complex. Outcrops along this side of the complex are scant. The only suggestion of 
emergence of fold axes is found in exposures in the bed of a small brook 2,300 feet east of Deep Creek 
Church, and here the structure is open to more than one interpretation owing to the difficulty of tracing 
out the contacts. The contacts as drawn on plate 1 are deliberately noncommittal. 

In summary, the evidence appears to favor the interpretation of the granitic complex as a lens with 
local irregularities of the contact due both to irregular granitization and to folding of the contacts. The 
northern termination of the lens appears to owe its domal form to second-order folding. The precise nature 
of the domal structure is obscure. The apparent arch structure of the metasedimentary rocks at the north 



22 Feldspar Deposits of the Bryson City District, North Carolina 

end of the dome likewise is due to second-order folding, but the lack of a traceable key horizon in these rocks 
makes it impossible to determine their larger structural pattern. 

The problems involved may be analogous to that presented by the gneiss domes (Oliverian, Pelham, 
Monson, Glastonbury) that occur in a belt extending southward through western New Hampshire into east- 
ern Massachusetts and Connecticut. These domes have been described in a series of papers by Billings and 
his co-workers 34 and by Balk 35 . In New Hampshire the domes are associated with the Ammonoosuc vol- 
canics, of which amphibolites are a prominent component. The foliation of the volcanic rocks swings around 
the ends of the Oliverian gneiss domes, but elsewhere in the surrounding terranes, the metasedimentary 
rocks characteristically show axial-plane foliation. No satisfactory explanation of the development of the 
domes has so far been advanced. 

Nature of the rocks originally occupying the area of the granitic complex. — Granitic gneisses have been 
developed at the expense of metasedimentary rocks in places, particularly along the eastern side of the com- 
plex; but in large part the rocks that have been granitized appear to have been hornblende and biotite 
schists, and to a less extent gabbro and metaperidotite. In part the hornblende and biotite schists affected 
are derived from gabbro and peridotite, and the question naturally arises as to whether all the hornblende 
and biotite schists may have this origin. No definite answer to this question can be given, but if all the 
hornblende and biotite schists are of this derivation, it is curious that recognizable remnants of the parent 
rocks should be so restricted in distribution. Furthermore, Keith 36 reports that many small bodies of peri- 
dotite are found in areas of the Roan gneiss, the characteristic rocks of which are hornblende gneisses and 
schists and their biotitic variants. Keith states that though the peridotites break through and cross the 
Roan gneiss, their association with the gneiss is both marked and close, a statement that is amply supported 
by his map of the Nantahala quadrangle. It seems likely, therefore, that most of the dark schists in the 
Bryson City area represent the Roan gneiss. It is noteworthy that according to Keith's map of the Nanta- 
hala quadrangle, the areas of Roan gneiss are typically lenticular. It is further noteworthy that of the five 
granite bodies appearing on the map of the Nantahala quadrangle three are partly or entirely enclosed in 
the Roan gneiss. 

PEGMATITES 

GENERAL STATEMENT 

More than 150 occurrences of pegmatite within the Bryson City area have been studied by the writer. 
The locations of 144 of them, including all occurrences known to have been prospected or appearing to have 
potential economic interest, are shown on plate 1. Thirty-six of the prospects are named in the accompany- 
ing lists. Fourteen of the more important and better exposed pegmatite bodies have been mapped, chiefly 
by plane-table methods, and studied in as much detail as warranted by exposures. Trenches and postholes 
have been dug at a few of the mines to obtain additional information, and systematic surface exploration of 
four pegmatite bodies has been done within limits imposed by the time available. Studies of pegmatite bod- 
ies in the district are considerably hampered by the paucity of exposures, particularly by lack of exposures 
of fresh rock. The structure and lithology of many of the pegmatites, therefore, are not fully indicated. 
For many, even surface outlines cannot be fully inferred at present. 



34 Billings, M. P., Regional metamorphism of the Littleton-Moosilauke area, New Hampshire: Geol. Soc. America Bull., vol. 48, pp. 
463-566, 1937. 

, Structure and metamorphism in the Mount Washington area, New Hampshire: Geol. Soc. America Bull., vol 52, 

pp. 863-936, 1941. 

__, Mechanics of igneous intrusion in New Hampshire: Am. Jour. Sci., vol. 243-A, Daly volume, pp. 40-68, 1945. 

Chapman, C. A., Geology of the Mascoma quadrangle, New Hampshire: Geol. Soc. America Bull., vol. 50, pp. 127-180, 1939. 
Chapman, C. A., Billings, M. P., and Chapman, R. W., Petrology and structure of the Oliverian magma series in the Mount Wash- 
ington quadrangle, New Hampshire: Geol. Soc. America Bull., vol. 55, pp. 497-516, 1944. 

Kruger, F. C, Structure and metamorphism of the Bellows Falls quadrangle of New Hampshire and Vermont: Geol. Soc. Amer- 
ica Bull., vol. 57, pp. 125-160, 1946. 

35 Balk, R., The Pelham gneiss dome, Massachusetts: Am. Geophys. Union Trans., pt. II, pp. 343-344, 1942. 
3(i Keith, Arthur, U. S. Geol. Survey Geol. Atlas, Nantahala folio (no. 143), p. 3, 1907. 



Feldspar Deposits of the Bryson City District, North Carolina 23 

DISTRIBUTION AND OCCURRENCE 

Most of the pegmatites examined during the present investigation lie along or near the border of the 
granitic complex that extends northeast and southwest from Bryson City, and most of the pegmatite mines 
and prospects lie along the northwest border. Nearly two-thirds of the 144 pegmatite occurrences shown on 
plate 1 lie within a belt 2,000 feet wide extending from the north end of the granitic complex southward along 
the west border of Alarka Creek, and including the territory for 1,000 feet on each side of the middle of 
the belt of border gneiss that bounds the complex. The distribution shown on the map is not a wholly accu- 
rate index of the distribution of pegmatites in the area for the following reasons. (1) The belt defined above 
has probably been more intensively prospected than the remainder of the area; (2) large portions of the 
granitic complex, particularly north of the Tuckasegee River, are concealed beneath terrace and floodplain 
deposits; (3) the map omits some minor stringers of pegmatites and emphasizes pegmatites that have been 
mined or prospected. Even allowing for these factors there is a marked concentration of pegmatites in the 
belt defined, and large pegmatite bodies are uncommon outside this belt. The largest known pegmatite body 
in the central part of the granitic complex, the DeHart pegmatite (pi. 1, no. 33, and pi. 19), is only about 220 
feet long and 90 feet in maximum width. The next largest, the pegmatite at the Nichols prospect (pi. 1, no. 
24) , is probably no more than 250 feet long and 30 feet in maximum width. The other known pegmatites, 
both in the central part of the granitic complex and along the eastern margin of the complex, are much 
smaller bodies, and many are little more than stringers. 

Most of the largest bodies of pegmatite in the district, including the pegmatites from which all but a 
small fraction of the production of feldspar has come, lie athwart and largely enclosed in the belt of border 
gneiss along the western margin of the complex. Only two large bodies, the Woody No. 1 pegmatite (pi. 1, 
no. 2) and the Randall pegmatite (pi. 1, no. 7), are known in the metasedimentary rocks outside this belt; 
both lie within 1,000 feet of the northwest margin of the belt of border gneiss. Other known pegmatite 
bodies in the metasedimentary rocks on both sides of the complex are small, mostly less than 100 feet in 
length. At most places along the western side of the granitic complex no pegmatites occur more than 500 
feet west of the border gneiss, but no eastern limit to the occurrence of pegmatites has been found. 

SIZE, SHAPE AND ATTITUDE 

The pegmatites of the district range from bodies less than 1 inch in thickness and less than 1 foot in 
length to bodies tens of feet in thickness and hundreds of feet in length. The largest known pegmatite of the 
district, the Deep Creek No. 1 pegmatite (pi. 10) , is 490 feet long and 40 to 210 feet in outcrop width, but 
the main pegmatite at the Randall mine may be more than 550 feet long. Most of the pegmatites appear to 
be less than 200 feet long and less than 50 feet in thickness. 

The pegmatites have various shapes. The pegmatites simplest in form are tabular bodies with parallel 
walls, and bodies that have the shape of flattened lenses. Some of the smaller bodies of pegmatite cutting 
granitic gneiss in the central part of the granitic complex exemplify this form. The larger bodies of peg- 
matite are commonly less simple in outline, but the shapes of the North McCracken pegmatite (pi. 15), the 
Harry Thomas pegmatite (pi. 8), and the Payne and Sullivan pegmatite (pi. 1, No. 35), approach a lenticu- 
lar form. The outlines of most of the larger bodies are complicated by bulges of the contacts outward into 
the country rock, reentrants of country rock into the pegmatite bodies, or offshoots of pegmatite into the 
wall rocks. Branching of both the larger and smaller bodies is common. Some of the resulting forms are 
highly complex; for example, those shown by the north Carson pegmatite (pi. 5), Deep Creek No. 1 pegma- 
tite (pi. 10), and DeHart pegmatite (pi. 19). 

Certain of the pegmatite bodies of the district appear to be pipe-shaped. The Carson south pegmatite 
(pis. 5, 6) appears to be an irregular- walled pipe, plunging southwest at a gentle to moderate angle; it has 
numerous offshoots along fractures in the country rock. The Swain pegmatite (pi. 8) likewise appears to 
be an irregular pipe, plunging about S. 60° W. ; and there are other bodies only partly exposed, such as the 
Cox No. 2 pegmatite (pi. 17), that may also have a pipelike form. In this connection it should be pointed 
out that the mines of the district are shallow. Deeper mining might show that the long axes of many of the 
pegmatites are steeply inclined. This relation has been proven for the Swain pegmatite, and allowing for 
erosion of the upper part of the Deep Creep No. 1 pegmatite, it is likely that the longest axis of this body 



24 Feldspar Deposits of the Bryson City District, North Carolina 

also plunges at a moderate angle. The relation probably holds true for some of the other pegmatites of 
the district; hence their over-all dimensions are probably greater than is apparent from their surface di- 
mensions. 

Data regarding attitudes of the pegmatites of the district are limited because many of the bodies are 
poorly and incompletely exposed. Observed dips and strikes cover a wide range, but there appears to be 
a relation between attitude and geologic occurrence. Pegmatites in the border gneiss belt along the north- 
west side of the granitic complex in general trend north-northwest to north-northeast across the northeast- 
erly trend of the border gneiss. Pegmatites in the metasedimentary rocks range from bodies that are mark- 
edly discordant, like the Randall pegmatite and the Woody No. 1 pegmatite (pi. 7), and of various attitudes, 
to concordant lenses that commonly strike northeasterly and dip west at steep angles. No generalizations 
can be made regarding the attitudes of pegmatite bodies in the granitic gneisses. 

STRUCTURAL RELATIONSHIPS TO ENCLOSING ROCKS 

The problem of the structural relations of the pegmatites to the enclosing rocks is one of the most in- 
teresting of the district and, owing to paucity of exposures, one of the most tantalizing. Fractures con- 
trolled emplacement of many of the pegmatites, and other pegmatites were emplaced along bedding and folia- 
tion of the metasedimentary rocks. The control of certain of the larger pegmatites in the border gneiss belt 
along the northwest margin of the granitic complex, however, is not so simple. The Branton, Cox, Deep 
Creek No. 1, Swain, and Carson pegmatites all are associated with asymmetric flexures of the margin of the 
granitic complex. In general, the flexures appear to have axes plunging at moderate to moderately steep angles 
to the southwest. There is a horizontal component of deformation such that the metasedimentary rocks appear 
to have moved northeast with respect to the granitic gneisses. Fractures related to these flexures appear to 
have served as an important structural control over pegmatite emplacement. Thus the Swain pegmatite (pi. 
8) lies in the axial portion of a flexure and plunges S. 60° W. about 45° parallel to the calculated axis of the 
flexure. Faulting of a flexure is clearly involved in the localization of the prominent westward bulge of the 
pegmatite body at the Deep Creek No. 1 mine (pi. 10). Faulting likewise may be involved at the north Car- 
son pegmatite. From the available data, it appears that the intersections of flexure-related fractures and 
the border gneiss horizon are the effective controls of emplacement of the more important feldspar-produc- 
ing pegmatites of the district. 

INTERNAL STRUCTURE 

General statement. — The pegmatites of the Bryson City district are mixtures of quartz, microcline-per- 
thite ("potash feldspar"), and sodic plagioclase ("soda feldspar"), subordinate to minor amounts of bio- 
tite or muscovite, or both, and traces of other minerals. Crystals of these minerals range in size from micro- 
scopic to as much as 22 feet in maximum dimension. Most crystals are between an inch and 8 feet in max- 
imum dimension. Four textural divisions based on grain size are recognized : 

Division Maximum dimensions of crystals 

Fine 1 inch or less 

Medium 1 inch to 4 inches 

Coarse 4 inches to 1 foot 

Very coarse 1 foot or more 

Exposed parts of some pegmatites are esentially uniform mixtures of their component minerals. Others 
show a more or less distinct arrangement of components into structural units of contrasting mineral compo- 
sition or texture, or both. As in other districts, 37 three types of structural units within pegmatites have been 
recognized in the Bryson City district. These types are (1) fracture-fillings, (2) replacement bodies, and 
(3) zones. The units are defined as follows: 

(1) Fracture- fillings are units that occupy fractures in previously consolidated pegmatite. They 

are commonly tabular. 



37 Cameron, E. N., Jahns, R. H., McNair, A. H., and Page, L. R., Internal structure of granitic pegmatites: Econ. Geology Mon. 2, 
113 pp., 1949. This paper summarizes the conclusions of a group of geologists of the U. S. Geological Survey regarding the 
structural features of pegmatites. A review of the literature of the subject is given in the paper. 



Feldspar Deposits of the Bryson City District, North Carolina 



25 



(2) . Replacement bodies are units formed primarily by replacement of preexisting pegmatite 
with or without obvious structural control. 

(3) Zones are successive shells, complete or incomplete, that reflect in various degrees the 
shape or structure of the pegmatite body. In ideal development, the zones of a pegmatite are suc- 
cessive shells concentric about an innermost zone or core. 

The general relationships of the three types of units are shown diagrammatically in figure 4. 




Figure 4. Idealized Diagram to Show Types of Pegmatite Units 

Pegmatite units in the Bryson City district range from tiny veinlike fracture-fillings to bodies hundreds 
of feet in length and tens of feet in width. Some units differ markedly from adjacent units in composition 
or texture, or both. Others have gradational boundaries and can be distinguished only by close study and 
comparison. In a few instances, one unit grades imperceptibly into another and only the contrast between 
typical parts of the units can be recognized. Two different investigators would agree in recognizing the 
units but would not agree, within close limits, on the positions of boundaries between units. This difficulty 
is particularly serious in the Bryson City district owing to the simple mineralogy of the pegmatites. Tour- 
maline, beryl, and other striking accessory minerals, which in some districts assist in delineating boundaries 
between structural units, are virtually lacking in the Bryson City district. In most of the units the essential 
minerals are feldspars and quartz. The units differ chiefly in texture and in proportions of these minerals, 



26 



Feldspar Deposits of the Bryson City District, North Carolina 




Carson South 



40 




<^4 



!>-) 



i^ -' \N 






\Ki\ -w. 






SCALE 




SCALE 







80 Feet 



SCALE 



"« = *• "« <y 
80 Feet •* >»\^ 



Harry Thomas 



20 



v>\MC ' 



SCALE 



j40FeetM|,>-r\:.--Pr<// 






iI<Li^ 



-7 




Wall rock 



Pegmatite, wall of 
McCracken No.6 working 
5 10 Feet 

I I 

SCALE 



\ /Deep Creek No I 
J 




80 l60Feet 



SCALE 



De Hart 



SCALE 



Figure 5. Shapes and Arrangement of Zones in Certain Pegmatites of the Bryson City District. 



Feldspar Deposits of the Bryson City District, North Carolina 



27 



and in general the contrasts between units are not marked. Structural units can be recognized in some of 
the pegmatites only on the basis of detailed mapping and structural analysis. 

Zones are quantitatively and economically by far the most important structural units in the pegmatites 
of the Bryson City district. Certainly more than 99 percent of the feldspar and kaolin output of the district 
has come from zones. Fracture-fillings are conspicuous in the Deep Creek No. 1 pegmatite, in the north Car- 
son pegmatite, and in the Swain pegmatite, and may have yielded a tiny fraction of the total output of kaolin 
and feldspar. Replacement bodies are minor features of a few of the pegmatites of the district. 

Zones. — The outstanding feature of zones is their concentric arrangement within pegmatite bodies. The 
zones reflect more or less accurately the configuration of the pegmatite walls. Ideally, zones are successive 
complete shells concentric about the innermost zone or core. In many pegmatites, however, one or more zones 
are incomplete or discontinuous, forming pods, layers, lenses, or pipelike bodies (figs. 4 and 5). There are 
all gradations between complete zones of nearly uniform thickness and those that are developed along one 
side or at one end of a pegmatite body. The zonal character of partly or asymmetrically developed units, 
however, is ordinarily readily recognized from their systematic relationship to the walls of the pegmatite 
body and to other zones of the pegmatite. Figure 5 shows variations in shapes and arrangement of zones 
in certain pegmatites of the district. 

Observations in the district indicate clearly that there is no relation between the size of a pegmatite body 
and the degree of development of zonal structure. Well-developed zonal structure of the kind found in the 
Deep Creek No. 1 pegmatite is shown likewise in certain smaller pegmatites (fig. 6) . On the other hand, a 
few of the larger pegmatites of the district are only indistinctly zoned. 



S.60°W N.60°E 

Granite gneiss with thin 
i-iC- ^ pegmatitic streaks and patches 




[1^1 

Perthite-plagioclase-quartz pegmatite 



Plagioclase-quartz pegmatite 
with minor biotite 



Border zone 
5 10 Feet 

SCALE 



Figure 6. Sketch of Small Pegmatite Body, McCracken No. 6 Working. 



According to their positions within pegmatites, zones have been classified 38 into four types: border 
zones, wall zones, intermediate zones, and cores, and this classification is followed in the present report. The 
use of this classification is shown in figure 4. The border zone, the outermost zone of a pegmatite, is com- 
monly a fine-grained selvage less than two inches thick. The wall zone, next inside the border zone, is gen- 
erally much coarser and ranges from 6 inches to several feet thick. The core, or innermost zone, is generally 
an elongate lens, a podlike body, or a pipelike body, located at or near the midportion of the pegmatite. In 
some pegmatites the core is discontinuous, composed of a series of disconnected pods or lenses (fig. 7). 
Any zone between the core and the wall zone is an intermediate zone. Many pegmatites have two or more 
intermediate zones which are distinguished by the use of such terms as outer, middle, and inner intermediate 
zones. The term "core-margin zone" is sometimes useful as a designation for the innermost intermediate 
zone. Zones, as well as other pegmatite units, are designated also by names that express their mineral com- 



1 Cameron, E. N., Jahns, R. H., McNair, A. H., and Page, L. R., The internal structure of granitic pegmatites: Econ. 
Mon. 2, 113 pp., 1949. 



Geology, 



28 



Feldspar Deposits of the Bryson City District, North Carolina 




Inner zones, including zones 
yielding commercial feldspor 



msmw s 



zones 



m 

Outer, non-producti\ 
Contact of pegmatite, with dip 



Vertical contact 



PLAN OF COX NO. I PEGMATITE 

O 4g §OFeel 

SCALE 



Figure 7. Plan of the Pegmatite Body at the Cox No. 1 Mine. Geology Partly Restored. 

position in terms of the most abundant minerals, thus: plagioclase-quartz-perthite pegmatite, perthite-quartz 
pegmatite. The order of the minerals in such a name is the estimated order of decreasing abundance. 

It has been frequently noted that the outer zones of a pegmatite are commonly more regular and more 
continuous than the inner zones, and this generalization, so far as it can be checked in limited exposures, 
holds true for the pegmatites of the Bryson City district. Intermediate zones, particularly the inner ones, 
are commonly lenticular and are so uneven in thickness or so incompletely developed that the internal struc- 
ture of a pegmatite may be markedly asymmetric. Inner zones in the Bryson City district are commonly lo- 
cated nearer the hanging wall than the footwall and are commonly best developed, as in other districts, in 
the thicker parts of a pegmatite body. The inner zones of the Deep Creek No. 1 pegmatite (fig. 8) are a 
noteworthy illustration. This generalization is important to the prospector, because the inner zones of the 
pegmatites of this district are the productive ones. 

The relative continuity of the wall and border zones is particularly well illustrated where there are septa 
or reentrants of wall rock extending into a pegmatite. The wall and border zones commonly follow in detail 
the wandering of the contact of pegmatite and wall rock. Inclusions of wall rock in a pegmatite (fig. 9), 
even if enclosed in an intermediate zone, are separated from the material of this zone by wall and border 
zones. 

Because asymmetry of internal structure is so common in pegmatites, limited exposures are seldom a 
reliable guide to the over-all structure of a pegmatite body. Zonal structure is a three-dimensional prob- 
lem. An apparent core at one level may prove to be an intermediate zone at another level (fig. 10), or a 
zone that is apparently a complete shell at the surface may be found to be discontinuous in depth. 

The border or outermost zone in pegmatites of the Bryson City district is commonly a fine-grained mix- 
ture of plagioclase and quartz with various amounts of perthite. Biotite, magnetite, and garnet are common, 
perhaps characteristic, accessory minerals, but in the exposed parts of some pegmatites these minerals, if 
ever present, have been destroyed by weathering and are represented by brown to black spots composed of 



Feldspar Deposits of the Bryson City District, North Carolina 



29 




EXPLANATION 



xxx 



Quartz-core 



x o x 
n x m 



Quartz-perthite pegmatite- 
inner intermediate zone 






Perthite-quartz pegmatite- 
middle intermediate zone 



jfrj 



Plagioclase -quartz- perthite pegmatite - 
outer intermediate zone 



z: 



Plagioclase-quartz pegmatite 
with minor perthite- 
wall and border zones 



Contact of pegmatite with 
wall rocks 



DEEP CREEK NO. I PEGMATITE 
PLAN AT ELEVATION 2150' 



100 



200FEET 



SCALE 



Figure 8. Plan of Deep Creek No. 1 Pegmatite at Elevation 2,150 Feet. 

limonite or manganese oxides or both. Biotite occurs in many of the zones as flakes up to 1 inch broad 
oriented roughly perpendicular to the contact of the pegmatite. The border zone, so far as determinable, 
is a continuous envelope enclosing the remainder of the pegmatite. Border zones commonly range from Vi 
to 1 inch in thickness, but locally are as much as 6 inches thick. They grade abruptly into adjacent wall 
zones by increase in grain size. The border zone is of no economic importance, but is useful in structural 
analysis. Its preservation along a contact is a strong indication that there has been no significant displace- 
ment ; conversely, its absence is a reliable criterion for the detection of fault contacts. 

The wall zones of the pegmatites are commonly medium- to coarse-grained mixtures of plagioclase and 
quartz with various amounts of perthite, and accessory to scarce biotite, muscovite, garnet, and magne- 
tite. In general, they range from 6 inches to 3 feet in thickness. Outward they pass abruptly, by decrease 
of grain size, into the border zones ; inward they pass gradually, by increase in grain size and commonly by 
change in mineral proportions, into intermediate zones. The most distinct wall zones, such as the wall zone 
of the Cox pegmatite, are rich in blocky plagioclase free of intergrown quartz. With increase in perthite 
and in amount of quartz in irregular or graphic intergrowth, they become progressively more difficult to 
distinguish from pegmatite of the outermost intermediate zone. This variation can be found within a single 
pegmatite. The wall zone in the Deep Creek No. 1 pegmatite (pi. 10), for example, is much more distinct 



30 



Feldspar Deposits of the Bryson City District, North Carolina 



in the vicinity of the main working than in the north working. Wall zones appear to have been prospected 
for kaolin in the early days of the district but are too thin to be important sources of feldspar. 

Intermediate' zones of the pegmatites are coarse to very coarse mixtures of plagioclase, perthite, and 
quartz, with accessory biotite or muscovite, or both, garnet, magnetite, and more rarely beryl, tourmaline, 
and allanite. Crystals of feldspar range in general from 1 foot to as much as 15 feet in length. The com- 







!r,l a I " 

p " *fP 
'=J| 



Intermediate zone 



fr 



I 



3 4 Feet 

_J 1 



SCALE 



Figure 9. Sketch Showing Development of Zones Around Inclusions in the Middle In- 
termediate Zone, Carson South Pegmatite. 




'°^%S^ 



Figure 10. Two Stages in the Exposure of a Pegmatite by Erosion. In the First Stage the Inter- 
mediate Zone Appears to Be the Core. 



Feldspar Deposits of the Bryson City District, North Carolina 

Plate 3. 



31 




A. Steeply dipping quartz fracture fillings (to left of opening) cutting pegmatite at mouth 
of chamber, Carson mine, No. 3 working. The most prominent fracture filling is about 4 inches 
in maximum thickness. 




B. Cox No. 1 mine. Upper part of main working at left, beneath derrick boom. 

monest type of intermediate zone is one consisting of plagioclase, quartz, and perthite. The perthite occurs 
in part as coarse to very coarse crystals partly or entirely in irregular to graphic intergrowth with quartz. 
This type of material is ordinarily not workable for feldspar. In some pegmatites this zone passes inward 
into a zone composed largely or almost entirely of coarse to very coarse plagioclase and perthite in graphic 
intergrowth with quartz. The second intermediate zone of the Carson south pegmatite is a particularly 
striking example. The inner intermediate zone of the north McCracken pegmatite is a variant of this zone, 
consisting largely of graphic intergrowths of perthite and quartz, with subordinate perthite free of inter- 
grown quartz. In the Deep Creek No. 1, Swain, and other pegmatites, the innermost intermediate zone, or 
pair of zones, consists essentially of very large crystals of perthite (up to 22 feet in maximum dimension at 
the Deep Creek No. 1 mine) and massive quartz forming the matrix of the perthite crystals. These inner 
intermediate zones are the source of the bulk of the commercial feldspar of the district. 



32 



Feldspar Deposits of the Bryson City District, North Carolina 



The cores of the well-zoned pegmatites commonly consist of massive quartz or of massive quartz with 
scattered crystals of massive perthite or plagioclase, or both. Such cores are exemplified by that of the 
Deep Creek No. 1 pegmatite (now largely removed), the cores of the Woody No. 1 pegmatite, the Woody 
No. 4 pegmatite (pi. 4), the Carson south pegmatite, and others. It seems probable that quartz cores are 
characteristic of distinctly zoned pegmatites of the district. Some pegmatites have apparent cores com- 
posed of other material, but the true cores may have been removed by erosion or may be concealed beneath 
the surface. The chances of removal or concealment are the greater because in most of the pegmatites 
known to have quartz cores, the core forms only a small fraction of the total bulk of the pegmatite. Cores 
of some of the pegmatites are discontinuous, consisting of disconnected segments occurring at intervals 
along the strike or dip. Cores of this type occur in the Cox No. 1 pegmatite (fig. 7), in the Deep Creek No. 
1 pegmatite (fig. 8, fig. 11), and in several smaller pegmatites in the district. Most of them are situated, 




EXPLANATION 



Quartz -perthite pegmatite 
Inner intermediate zone 

Perthite-quartz pegmatite 
Middle intermediate zone 

Plagioclase- perthite-quartz pegmatite 
Outer intermediate zone 



Plagioclase-quortz pegmatite 
with minor perthite 
Wall and border zones 



/\ Plagioeiase-quortz p 

<^><^> with minor perthite 

^-^ Wall and border zon 

<^/^> Contact of pegmatite with woll rocks 

<C~^ > Limit of underground working 



Figure 11. Isometric Plate Diagram Showing Arrangement of Zones in 

the Deep Creek No. 1 Pegmatite. 



Feldspar Deposits of the Bryson City District, North Carolina 



33 



together with the other inner zones, in the broader parts of the pegmatites, and are nearer the hanging wall 
than the footwall. 

Sequence of mineral assemblages in the zoned pegmatites. — In the course of wartime studies of pegma- 
tites by the U. S. Geological Survey it was noted that the pegmatites within a given district have similar 
zonal structures and also similar sequence of assemblages of essential minerals in the zones inward from the 
walls. For any district, it is possible to draw up a general, sequence of mineral assemblages. Few pegma- 
tites in a district contain zones corresponding to all the members of the sequence. Members are lacking in 
some pegmatites, in others a single zone, contains minerals belonging to two or more adjacent members of 

Plate 4. 




Quartz core of Woody No. 4 pegmatite. 



the sequence. In any given pegmatite, the mineral assemblages present occur in an order from the walls 
inward that corresponds to the general sequence. Comparison of pegmatite bodies of various districts stud- 
ied during the war led to a recognition of a general sequence of mineral assemblages that holds for all but 
a very few of the many hundreds of pegmatites examined. 39 The general sequence recognized, from the 
walls of the pegmatites inward, is as follows : 

1. Plagioclase-quartz-muscovite. 

2. Plagioclase-quartz. 

3. Plagioclase-quartz-perthite, with or without muscovite, with or without biotite. 

4. Perthite-quartz or quartz-perthite. 



39 Cameron, E. N., Jahns, R. H., McNair, A. H., and Page, L. R., The internal structure of granitic pegmatites: 
Mon. 2, 113 pp., 1949. 



Econ. Geology, 



34 Feldspar Deposits of the Bryson City District, North Carolina 

5. Perthite-quartz-plagioc 1 ase-amblygonite-spodumene. 

6. Plagioclase-quartz-spodumene. 

7. Quartz-spodumene. 

8. Lepidolite-plagioclase-quartz. 

9. Quartz-microcline. 

10. Microcline-plagioclase-lithia mica-quartz. 

11. Quartz. 

In some pegmatite districts only a few members of the general sequence have been found in the pegma- 
tites thus far studied ; those members found, however, occur in an order from the walls inward correspond- 
ing to the sequence above. 

A clearly defined sequence of mineral assemblages likewise is found in the pegmatites of the Bryson 
City district. The general sequence for the district is given in table 1, together with the sequences of min- 
eral assemblages for 26 pegmatites of the area. For each pegmatite, the order in which the mineral assem- 
blages present are read from left to right is the order in which zones corresponding composition are found 
from the walls of the pegmatite inward to the core. No exceptions to this order have been found. However, 
one anomaly is shown in the table. The third member of the general sequence is perthite-quartz pegmatite. 
This member typically consists of very large massive perthite crystals with interstitial coarse massive 
quartz. In many of the pegmatites, however, such as the Carson north pegmatite, the zone having the 
sequential position of the perthite-quartz assemblage contains plagioclase crystals similar in size and habit 
to the perthite. Blocky plagioclase is present in equal, perhaps greater, amounts than perthite in the Carson 
south pegmatite, and blocky plagioclase is present to the exclusion of perthite in the Woody No. 4 pegma- 
tite. With increase in plagioclase, the assemblage becomes similar in mineral composition successively to 
the second and first members of the general sequence, but it invariably resembles the perthite-quartz mem- 
ber closely in texture and is in striking and consistent contrast to the other two members of the sequence. 



Table 1. Sequence of Mineral Assemblages in 26 Pegmatites of the Bryson City District 





I 

Plagioclase- 

quartz- 
muscovite 


II 

Plagioclase- 
quartz, with 
minor to sub- 
ordinate 
perthite 


Mineral Assemblages 


Pegmatite 


III 

Plagioclase- 

quartz- 

perthite 


IV 
Perthite 
quartz 


V 

Perthite- 

plagioclase- 

quartz 


VI 
Quartz- 
perthite 


VII 
Quartz 


Woody No. 1 




X 
X 


X 
X 




X 


X 


X 


Woody No. 2 








Woody No. 4 






X 




X 


Carson north 




X 
X 
X 


X 
2 X 
X 
X 
2 X 
X 
X 
X 
X 
X 
2 X 
2 X 


X 


X 


X 


Carson south 




X 


X 


Randall 










No 8 prospect 




!X 

X 






•X 


Swain _ 




X 


X 
X 




X 


H. Thomas. 




3 X 
X 
l X 




Deep Creek No. 1 




X 
X 
X 
X 
X 
X 
X 


X 
X 


X 


N. McCracken ..'. 






*X 


McCracken, west cut 




X 
X 




S. McCracken 










Cox No. 1 




X 
X 
X 




X 


Cox No. 2 










Hyatt No. 2 prospect 










Branton No. 1 




2 X 
2 X 
X 
X 


*X 
iX 


X 




Cochran... _ 








!X 


Nichols prospect 1. 




X 


X 


X 




Ball No. 1 








Ashe Thomas 


X 




X 






X 


DeHart No. 1... 


X 


X 
X 


X 


X 




Simon DeHart 


X 


X 




D. Thomas No. 1 _ 


X 
X 
X 


X 
X 
X 




X 


Hans No. 1 












Payne and Sullivan 




X 




X 













1 In pods. 

2 Two zones differing in texture. 

3 Perthite content higher than normal. Transitional between members IV and VI. 

4 Position of unit in sequence uncertain. 



Feldspar Deposits of the Bryson City District, North Carolina 35 

It is therefore regarded as a variant of the perthite-quartz assemblage. Plagioclase occurring in this unit 
may, in part at least, have formed by replacement of preexisting perthite. Laboratory studies will be re- 
quired to test this possibility ; field observations have left the matter unsettled. 

Of the 11 members of the general sequence recognized by comparison of sequences for various districts, 
only members 1, 2, 3, 4, and 11 are represented in the pegmatites of the Bryson City district, a generalization 
that serves to emphasize their mineralogical simplicity. Member I of the Bryson City sequence corresponds 
to member 1 of the general sequence, member II is transitional between members 2 and 3, member III is 
equivalent to member 3, members IV and VI are subtypes of member 4, and member VII corresponds to 
member 11 of the general sequence. Member V is anomalous with respect to the general sequence. 

Owing to this anomaly, a consistent sequence of assemblages cannot be recognized at present on the 
basis of mineralogy alone, but a consistent sequence is evident if both mineralogy and texture are taken into 
account. Member I of the sequence consists essentially of medium- to coarse-grained plagioclase all or 
nearly all free of intergrown quartz, subordinate interstitial quartz, and muscovite. Member II is similar but 
lacks muscovite and in some pegmatites contains subordinate to minor perthite. Graphic intergrowths of 
feldspars and quartz are rare in these two members. Member III of the sequence consists of coarse to very 
coarse plagioclase-quartz-perthite pegmatite with numerous graphic to irregular intergrowths of feldspars 
and quartz. Inward toward the core this member becomes rich in graphic intergrowths and the inner part 
may consist almost entirely of graphic intergrowths. The two f acies are mappable as separate zones in the 
Carson south pegmatite and in the Cox No. 1 pegmatite. Member IV of the sequence consists essentially of 
perthite and quartz, the quartz occurring as coarse masses interstitial to large, quartz-free crystals of per- 
thite. The inner intermediate zone of the McCracken pegmatite, which contains much perthite in graphic 
intergrowth with quartz, is clearly a type transitional between members III and IV of the sequence. Mem- 
ber IV, just described, and member V are not found in the same pegmatite, although various pegmatites 
show every gradation between the two. Member VI of the sequence consists of large crystals of perthite 
scattered through quartz, and member VII consists entirely of massive quartz. 

It is essential that a clear distinction be made between mineral assemblages and zones. A single min- 
eral assemblage may be represented in a pegmatite by two or more zones differing in textural fabric or in 
the presence or absence of an accessory mineral. Thus the wall zone and outer intermediate zone of the 
Branton pegmatite are both composed of material corresponding to the second member of the general se- 
quence. The wall zone, however, contains both biotite and muscovite, whereas biotite is lacking in the 
intermediate zone. In the McCracken pegmatite, on the other hand, members IV, VI, and VII of the sequence 
are represented only by pods consisting of lenses of quartz with large perthite crystals along the margins. 
The sequence therefore serves as a basis for predicting where a given mineral assemblage, if present, will be 
found within a pegmatite. Whether a distinct zone corresponding to the mineral assemblage is present can 
be determined only by investigating the appropriate part of the pegmatite. 

It should further be noted that the terms "border zone," "wall zone," etc., are used without reference to 
composition. In pegmatites in which the plagioclase-quartz assemblage is present, this assemblage forms 
the border and wall zones. In pegmatites in which this assemblage is lacking, plagioclase-quartz-perthite 
pegmatite commonly forms the border and wall zones. 

Fracture-fillings. — Fracture-fillings are found in many of the pegmatites of the district. They range 
from bodies less than an inch thick and a few inches long to tabular bodies 3 feet thick and 50 feet or more 
in length along strike and dip. The simplest are the tabular bodies, which occupy parallel fractures. Frac- 
ture-fillings of this kind are a conspicuous feature in the main working and south working at the Deep Creek 
No. 1 mine, and are found in the Carson north pegmatite (pi. 3, A) , the Swain pegmatite, and other pegma- 
tites of the district. The fillings cut across the middle and outer zones of the pegmatites, and some extend 
out into the wall rocks. In places fillings of similar nature occupy networks of fractures. Complex net- 
works of veins cut the outer zones of the Deep Creek No. 1 pegmatite in the main working (pi. 10), and 
similar networks appear to be represented in the north wall of the No. 1 working at the Carson mine. 

Fracture-fillings in the Bryson City district are simple in mineralogy ; they commonly consist of quartz 
with subordinate to minor amounts of perthite or plagioclase, or both. Many of the fillings, such as those in 
the Deep Creek No. 1 pegmatite, are zoned; feldspars form an irregular, discontinuous selvage along each 



36 Feldspar Deposits of the Bryson City District, North Carolina 

wall and project inward into the quartz which forms the medial portion of each filling. The feldspar crystals 
are invariably euhedral against the quartz. The boundaries of fracture-fillings in weathered feldspathic 
pegmatite are commonly obscure, because the feldspar selvages are difficult to distinguish from the pegma- 
tite of the walls. At first sight the boundaries may appear to be at the margins of the medial quartz "rib." 

The fracture-fillings consisting predominantly of quartz or of quartz and feldspar are closely analogous 
in composition and textural fabric to the quartz and quartz-perthite zones found in the central parts of such 
bodies as the Carson south pegmatite, Deep Creek No. 1 pegmatite, and Swain pegmatite. One fracture- 
filling observed by R. H. Jahns (pi. 8, plan of workings at elevation 2,122 feet) at the Swain mine in 1945 
was a direct offshoot of the quartz core. Most of those exposed in the north wall of the main working of the 
Deep Creek mine are probably related to the quartz core of the pegmatite in the same way, but the part of 
the pegmatite in which junctions of fillings and core would be expected has been removed in mining. 

Smaller fracture-fillings, widespread in the district, consist of single books or groups of slablike books 
of biotite or muscovite, or both, along fractures or networks of fractures cutting quartz and feldspars, espe- 
cially in the inner zones of the pegmatites. In some pegmatites there are parallel striplike crystals of bio- 
tite that appear to be at least partly fracture controlled. Veinlets of pyrite cutting feldspars in the Deep 
Creek No. 1 pegmatite, veinlets of thulite(?) cutting feldspar in the Carson south pegmatite, and veinlets 
of quartz and muscovite in the inner zones of the Carson south pegmatite are rarer types of fracture-fillings 
observed. Fracture-fillings of quartz with minor feldspar are of interest because they appear to form a 
link between the more normal pegmatites and pegmatitic quartz veins scattered through the district. The 
latter are similar in composition to the fracture-fillings. Some, however, differ in that the quartz is gray to 
blue-gray and almost chalcedonic in appearance. Commonly they contain, in addition to quartz, only 
sparsely scattered crystals of perthite. Numerous small quartz veins or lenses with minor amounts of 
feldspars and muscovite are present in the metasedimentary rocks along the eastern margin of the granitic 
complex. They have been prospected at several places for mica or for feldspar. Various occurrences appear 
to show every gradation between the "veins" and more normal pegmatites. 

Lenses of coarse quartz are common in the metasedimentary rocks, especially west of the granitic com- 
plex, and presumably are the source of the small amounts of gold said to have been panned from the gravels 
of Bryson Branch and other streams of the area. The relation of these lenses to the pegmatites is not known. 

Replacement bodies. — Replacement bodies, a conspicuous feature of certain pegmatites in various dis- 
tricts, 40 are small and of minor importance in the Bryson City district. In places in the Deep Creek No. 1, 
Carson north, Swain, and other pegmatites, perthite has been partly replaced by albite(?) and greenish, 
fine-grained muscovite. The total amount of perthite involved is apparently very small. 

WALL ROCK ALTERATION 

Alteration of wall rocks adjacent to the pegmatites is not a prominent feature of the Bryson City dis- 
trict. Most contacts of pegmatites with wall rocks are sharp and well defined, although locally border gneiss 
an inch to a foot from pegmatite contacts has been converted to biotite aplite. Wall-rock alteration, where 
present, is commonly restricted to increase in the feldspar content of enclosing rocks. The most striking 
alteration is at the McCracken mine. Granite gneiss in the walls of the main working has been extensively 
"soaked" with pegmatite material, to the extent that in many places contacts between pegmatite and gneiss 
are gradational. Probably no great chemical change is involved ; the chief effects appear to be coarsening of 
texture and obliteration of gneissic structure. A different type of alteration related to pegmatite development 
may be represented in the metasedimentary rocks along the eastern side of the granitic complex. In places 
there are abundant coarse lenses and streaks of quartz and feldspar along the foliation of the metasedimen- 
tary rocks; muscovitization of quartzite and marked coarsening of the texture of muscovite schists are 
other effects observed. In places, a coarse mixture of quartz and muscovite, similar to the burr rock of the 
Spruce Pine and other southern mica districts, has been developed. The limited nature of exposures and 
the weathered condition of the metasedimentary rocks have prevented detailed analysis of alteration effects 
in this part of the area. 



40 Jahns, R. H., Mica deposits of the Petaca district, Rio Arriba County, New Mexico: New Mexico Bur. Mines and Min. Resources 
Bull. 25, pp. 48-51, 1946. 



Feldspar Deposits of the Bryson City District, North Carolina 37 

MINERALOGY 

General statement. — The pegmatites of the Bryson City district are extremely simple in mineralogy, con- 
sisting almost entirely of quartz and feldspars, with minor amounts of biotite or muscovite, or both. The 
commonest accessory minerals are magnetite and garnet. Tourmaline, allanite, beryl, fluorite, pyrite, thu- 
lite(?), and galena (?) are scarce minerals in the district. 

Feldspars. — The name feldspar is applied to a group of alkali-bearing aluminum silicates; the group is 
commonly divided into potash feldspars and the soda-lime feldspars. The potash feldspars are orthoclase and 
microcline (KAlSi 3 8 ) ; the soda-lime feldspars comprise a series ranging from albite (NaAlSi 3 8 ) to anor- 
thite (CaAl 2 Si 2 8 ). The feldspars of the pegmatites of the Bryson City district are perthite (microcline 
with subordinate albite in oriented, intergrown thin lamellae) , and sodic plagioclase probably ranging from 
albite to oligoclase (90-70 percent albite, 10-30 percent anorthite). 

Perthite forms crystals ranging in maximum dimension from fractions of an inch to as much as 22 feet. 
Most of the crystals are between an inch and 10 feet in length. In general the smaller crystals are found in 
the outer zones of the pegmatites, the larger crystals in inner zones. In most pegmatites of the district 
perthite (if present) is found in every zone except the quartz core, but it is most abundant in the inner inter- 
mediate zones. Certain of these zones, such as the middle intermediate zone of the Deep Creek No. 1 peg- 
matite (pi. 11), contain a high proportion of coarse perthite. In parts of a pegmatite in which the feldspar 
content is high, perthite generally occurs as poorly formed crystals. In general, perthite exhibits crystal 
form against massive quartz of the inner zones, and crystals of perthite surrounded by quartz are almost in- 
variably euhedral. In degree and type of its intergrowth with quartz, perthite shows a systematic varia- 
tion inward from the walls of multi-zoned pegmatites. In the wall zone and outer intermediate zones, much 
of the perthite is intimately intergrown with quartz. The intergrowths are mostly irregular, but in part are 
of the graphic type. In middle intermediate zones the proportion of perthite forming graphic intergrowths 
with quartz is high, some perthite free of quartz is found, and irregular intergrowths are uncommon. In 
inner intermediate zones, such as the perthite-quartz zone and quartz-perthite zones of the Swain and Deep 
Creek No. 1 pegmatites and the perthite-plagioclase-quartz zone of the Larson south pegmatite, most or all 
of the perthite is free of intergrown quartz. Perthite in fracture-fillings and feldspar-bearing -quartz veins 
likewise is free of intergrown quartz. 

Fresh perthite from the various pegmatites has a glassy luster and ranges from white through cream to 
buff, light greenish-buff, pink or flesh-colored, or reddish brown. White feldspar irregularly splotched with 
light gray is found in a few pegmatites but is decidedly uncommon. The microcline component of perthite 
is resistant to weathering, and parts of pegmatites in which plagioclase is completely altered may contain 
hard perthite differing from unweathered material only in being dull in luster and stained red to brown by 
iron oxides along cleavages and fractures. More severe weathering causes alteration of the thin plates of 
intergrown albite, and disintegration of the microcline to a crumbly mass or even to fine "sand." 

Plagioclase forms crystals similar in size range to those of perthite, except that crystals of plagioclase 
more than 8 feet in length are uncommon. In crystal habit there is a close similarity between perthite and 
plagioclase, and the plagioclase shows a comparable variation from zone to zone in habit and in degree and 
kind of intergrowth with quartz. In the majority of the pegmatites, however, plagioclase is not an abund- 
ant constituent of the innermost zones, which apart from quartz cores are predominantly perthite-rich. As 
noted previously, however, plagioclase is as abundant or even more abundant than perthite in the inner 
zones of certain pegmatites. The genetic relationship of plagioclase to perthite in these zones is one of the 
most interesting problems of the district. Field study was without conclusive results, and no generalizations 
appear warranted pending laboratory study. The abundance of plagioclase in graphic intergrowth with 
quartz is particularly noteworthy. Graphic intergrowths of perthite and quartz are a common feature of 
pegmatites in many districts, but the writer knows of no other district in which graphic intergrowths of 
plagioclase and quartz are a characteristic feature of the pegmatites. These intergrowths are present in 
profusion in every well-exposed and distinctly zoned pegmatite in the Bryson City district. In the Carson 
south pegmatite, the middle intermediate zone consists almost entirely of graphic intergrowths of quartz and 
perthite or plagioclase, intergrowths with plagioclase predominating. 



38 Feldspar Deposits of the B.ryson City District, North Carolina 

Plagioclase is white to pale gray except where stained brown by limonite or black by manganese oxides. 
All or nearly all crystals show multiple twinning, indicated in fresh material by fine parallel lines that ap- 
pear when light is reflected from the proper cleavage surface. This and its common pure white color usually 
serve to distinguish plagioclase from perthite, but distinction between the two feldspars is extremely diffi- 
cult in the core-margin zone of the Carson south pegmatite, which contains white perthite as well as plagio- 
clase. Plagioclase in weathered portions of pegmatites is converted to white, compact kaolin, some of high 
purity, and this is readily distinguished from hard, relatively unaltered perthite and from the gritty prod- 
ucts of perthite disintegration. 

Quartz. — Quartz occurs in every type of structural unit found in the pegmatites of the district. It forms 
minute grains, spindles, and elongate plates in graphic intergrowth with both plagioclase and perthite, irreg- 
ular intergrowths of varied texture with feldspars, coarse-grained masses interstitial to feldspars, and larg- 
er bodies that constitute the cores of some of the pegmatites. It is invariably anhedral against the feld- 
spars. Quartz crystals lining cavities rarely occur in the district. 

Quartz ranges in color from clear and colorless to white or milky, to gray, or to faintly smoky. Most 
quartz in the larger bodies appears to be coarse-grained and has a glassy luster, but some in the feldspathic 
quartz veins and fracture-fillings is dull, dense, and apparently fine-grained. In some pegmatites, notably in 
the quartz-perthite zone of the Carson north pegmatite exposed in the No. 1 working, shearing has caused 
the development of several sets of fractures and granulations of the quartz. 

Biotite. — Biotite is the characteristic mica of the pegmatites in granitic gneisses and the border gneiss. 
In border zones it occurs as thin flakes or striplike crystals % mcn to V2 mc h in length. In wall zones it 
occurs mostly as sparsely scattered books up to 3 inches broad and ^2 i ncn thick. In outer and middle inter- 
mediate zones it is found as striplike crystals ranging from 2 inches long, Vi inch wide, and 1/64 inch thick 
up to 32 inches long, 4 inches broad, and 2 inches thick, and occurs also in slabby books, many deformed, up 
to 214 feet broad and 6 inches thick. Some crystals in the Cox No. 1 pegmatite are partly chloritized. The 
striplike crystals of biotite are commonly haphazardly oriented, but the clusters consist of various crystals 
lying in a single plane and forming ^crisscross, rosette, or spray-like patterns. The crystals transect quartz 
and feldspars and appear to be fracture-controlled. A variant of the striplike habit is particularly well dis- 
played at the No. 3 working of the Carson mine. Here fracture surfaces are coated with composite crystals 
of biotite composed of parallel strips up to 1 foot long, 1 inch wide, and 1 inch thick. Part of one such com- 
posite crystal (the remainder has been mined out) measures 5 feet long, 1 foot broad, and 1 inch thick. 
Another is 7 feet long and 2 inches thick ; the width is not shown. The fractures cut quartz and feldspars 
and are plainly later. The slabby books of biotite are found in all zones but are particularly characteristic 
of the intermediate zones and core. They are developed along fractures of one or more sets cutting quartz 
and feldspars. A most striking occurrence of fracture-controlled biotite is indicated, in generalized form, 
on the plan of the 2,073-foot level of the Deep Creek No. 1 mine (pi. 11). Here biotite books 1 to 6 inches 
broad and up to 3 inches thick form an intricate network occupying closely spaced fractures. The frac- 
tures transect the outer part of the quartz-perthite zone and the inner part of the perthite-quartz zone. The 
master fractures strike N. 55° E. and dip 76° NW. They are connected by oblique fractures and, where the 
network intersects feldspar, by fractures parallel to the cleavages of feldspar. Part of this fracture-con- 
trolled body of biotite has been removed. The remaining part is 3 feet thick and is exposed for 12 feet ver- 
tically and for 8 feet along the strike. It is evident that biotite, in considerable part at least, has formed 
after consolidation of much or all of the pegmatite body. Biotite occurs in the Swain pegmatite as flakes 
along fractures cutting quartz-feldspar fracture-fillings and occurs at the Randall mine with muscovite in an 
irregular network of quartz veinlets cutting the outer intermediate zone. 

The surfaces occupied by biotite strips are in many places coated by greenish sericite, and a selvage of 
plagioclase and sericite or fine-grained greenish flake muscovite is developed where they cut feldspar. The 
selvages range from fractions of an inch to 3 inches or more in thickness. 

Biotite in parallel intergrowth with muscovite is common in the Branton, Cochran, Randall, Woody No. 
1, and other pegmatites. Striplike crystals of biotite and muscovite as much as 10 feet long, 6 inches wide, 
and 2 inches thick are found in the Woody No. 1 pegmatite. 



Feldspar Deposits of the Bryson City District, North Carolina 39 

In weathered parts of the pegmatites, vermiculite has formed from some of the biotite books. Its bronze 
color may serve to distinguish it from biotite. Some of it exfoliates when heated, but various specimens 
show very different capacities for exfoliation. 

Muscovite. — Muscovite is abundant in a few of the pegmatites within the granitic complex and is the 
characteristic mica of pegmatites in the metasedimentary rocks. It shows a wide range of colors — pale 
green, gray-green, amber, rum, and ruby. It forms crystals ranging from microscopic size (sericite) to 10 
feet in maximum dimension. The maximum diameters of crystals, however, lie mostly in the range between 
1/8 inch to 8 inches. The crystals range from anhedral and highly irregular to euhedral. Commonly the max- 
imum dimensions of crystals lie in the plane of the cleavage, but the outer intermediate zone at the Bran- 
ton mine contain anhedral books that are elongate parellel to the c axis and are as much as 4 inches in 
length. The books are embedded in quartz. Muscovite shows the same range in habit as biotite, occurring 
as flakes, slabby books, and striplike crystals. All these habits may be shown in the same pegmatite, as, 
for example, in the Woody No. 1 pegmatite. In the outer intermediate zone of the pegmatite at the Branton 
mine, muscovite crystals as much as an inch in diameter form single books, together with nests of books, 
as much as 8 inches by 4 inches in diameter. Books of gray-green muscovite as much as 1 foot long, 6 inches 
broad, and 4 inches thick are numerous along the margin of the quartz core. In the beryl-bearing unit of 
the pegmatite, books up to 10 inches broad and y% inch thick lie at the centers of irregular bodies of "burr 
rock" consisting of quartz thickly intergrown with small muscovite books. In the Cochran pegmatite irreg- 
ular bodies of burr rock up to 6 by 2 feet in cross section enclose tapered strips of biotite up to 18 inches 
long, several inches broad, and IV2 inches thick. In the DeHart pegmatite, muscovite books 2 inches broad 
or less form striking aggregates in the outer intermediate zone. 

Small flakes and books of muscovite are common in thin quartz fracture-fillings in many of the pegma- 
tites. In some pegmatites such as the Carson pegmatites, and the Swain, Deep Creek No. 1, and McCracken 
north pegmatite, perthite has been partly replaced by plagioclase, now kaolinized, containing disseminated 
small crystals of greenish muscovite. 

Distribution of biotite and muscovite. — Comparison of the distribution of biotite and muscovite in the 
pegmatites of the district as a whole indicates that there is a broad relationship between .the relative 
abundance of the two micas and the type of country rock. In pegmatites in granitic gneisses and in border 
gneiss, biotite is the characteristic mica and is normally far more abundant than muscovite. Whatever mus- 
covite is present is largely in fracture-fillings with quartz, as coatings on small fracture surfaces, or asso- 
ciated with plagioclase in aggregates formed by replacement of perthite. Muscovite in general predomi- 
nates over biotite in pegmatites in metasedimentary rocks and appears to be the only mica present in many 
of these pegmatites, particularly the small bodies scattered through the metasedimentary rocks along the 
eastern margin of the granitic complex. This relationship appears to be shown within the limits of a single 
body in the Carson north pegmatite. Muscovite is the characteristic mica of the part of the body exposed in 
the No. 1 working where the wall rocks of the pegmatite, at least on one side, are metasedimentary rocks. Biotite 
is abundant in the No. 3 working where border gneiss forms the wall rock, whereas muscovite is present only 
in late-stage material and in minor amounts. Inasmuch as muscovite is abundant in the metasedimentary 
■ rocks and commonly lacking or only a minor component in the rocks of the granitic complex, the distribu- 
tion of the mica suggests that reaction of pegmatitic fluids with the enclosing wall rocks has influenced the 
type of mica formed. 

Although a broad relationship of type of mica to type of wall rock is evident, there are numerous excep- 
tions. Muscovite and biotite are both abundant in the Woody No. 1 deposit, and biotite appears to be the 
predominant mica in the Woody No. 2 prospect. Biotite is moderately abundant in the Randall pegmatite, 
though less so than muscovite. All three of these pegmatites are in metasedimentary rocks. In the DeHart 
pegmatite, in granitic gneiss, muscovite is moderately abundant though subordinate to biotite. In the Bran- 
ton pegmatite, which is almost entirely in border gneiss and granitic gneiss, and in the Cochran pegmatite, 
which is mostly in border gneiss, muscovite is more abundant than biotite. Biotite appears to have devel- 
oped earlier than muscovite where the two micas are intergrown or in close physical association, but no 
over-all difference in time of deposition has been recognized. The crystallization of biotite in pegmatites 
in border gneiss appears to have begun earlier than that of muscovite, for only biotite is found in the border 



40 Feldspar Deposits of the Bryson City District, North Carolina 

and wall zones (apart from muscovite-bearing fracture-fillings) ; but deposition of both evidently continued 
into the final stages of pegmatite development, for both minerals occur in large part as fracture-fillings. 

Other minerals. — Garnet occurs in many of the pegmatites of the district as scattered red trapezohedral 
crystals generally 1/16 to 1/4 inch in diameter. As garnet is readily destroyed by weathering, it is probably 
considerably more widespread than is evident from the exposures available. It is present in every pegmatite 
in which unweathered material is exposed. Garnet is commonly a minor accessory, but closely spaced garnet 
crystals form striking aggregates up to a foot in diameter in the core-margin zone of the Carson south peg- 
matite. Crystals as much as an inch in diameter are found in some pegmatites, and in the DeHart mine 
3-inch crystals are present. Garnet is not confined to any one zone of a pegmatite, but in general it is more 
common and coarser in inner zones than in outer zones. 

One extraordinary occurrence of garnet indicates that in part it has developed relatively late in the 
period of pegmatite formation. In the south working of the DeHart mine closely spaced garnet crystals 
1/16 to 1/4 inch in diameter occur along planar to sinuous surfaces cutting the outer intermediate zone at 
high angles. Thickly disseminated garnet crystals occur also in feldspathic pegmatite adjacent to a frac- 
ture-filling of quartz about 14 inches long and 1 inch thick. 

Magnetite forms scattered crystals in many of the pegmatites and like garnet may be much more wide- 
spread than is indicated by the prevailing weathered exposures. It is found chiefly in border, wall, and 
outer intermediate zones, as unevenly scattered crystals or groups of crystals 1/16 inch to 1 inch in diam- 
eter. It appears to be most abundant in border zones where adjacent border gneiss has been aplitized. 
Crystals are octahedral in habit, range from euhedral to anhedral, and have prominent octahedral parting. 

Tourmaline and allanite have been found only in the Deep Creek No. 1 pegmatite where they occur 
along the gradational boundary between the perthite-quartz and quartz-perthite zones. Tourmaline forms 
rod-shaped aggregates of elongate, flattened, striated black parallel prisms as much as 4 inches by 1 inch in 
cross section and 1 foot or more in length. The aggregates reach a maximum length of 5 feet and are as 
much as 6 inches by 1 foot in cross section. The crystals are embedded in quartz and perthite and extend 
across the boundaries of the two minerals. Most of the tourmaline prisms are slightly bent, fractured, and 
faulted normal to their long axes. Quartz heals the cross-fractures. The quartz surrounding one such 
aggregate in the drainage tunnel of the main working shows a remarkable system of radial fractures ex- 
tending outward from the aggregate as much as 2 feet. 

In some of the aggregates tourmaline is partly embedded in black lustrous allanite which forms round- 
ed to irregular coarse-grained masses that have been fractured and veined by late feldspar and quartz. 
Feldspar adjacent to allanite shows the characteristic reddish discoloration resulting from radioactivity. 

The occurrence of allanite and tourmaline from top to bottom of the Deep Creek No. 1 mine, and only 
in the gradation between the perthite-quartz and quartz-perthite zones, is noteworthy. As the boundary 
between the zones is- gradational, there is no true contact surface which might serve as a structural control 
for tourmaline and allanite deposited after consolidation of the zones. Furthermore, the adjacent quartz 
and feldspar vein the allanite and tourmaline, and are evidently later, though probably only slightly later. 
It seems evident that tourmaline and allanite were formed during the period when the deposition of the 
material of the perthite-quartz zone was giving way to deposition of the quartz-perthite pegmatite. 

Beryl occurs only in the Branton pegmatite where it is found in sparsely scattered, yellowish-green, 
partly kaolinized crystals and columnar groups of parallel crystals at least 7 by 5 by 4 inches in maximum 
size. The crystals are restricted to a unit which is probably the inner intermediate zone of the pegmatite. 

Pyrite, fluorite, and galena are late minerals, occurring along fractures cutting other minerals. Pyrite 
has been observed in several pegmatites, purple fluorite only as traces in the Cox No. 1 pegmatite, and galena 
only as traces in the Cox No. 1 and Carson south pegmatites. 

Weathering products of the pegmatite minerals include kaolin, limonite, and manganese oxides, in addi- 
tion to the vermiculite previously described. Kaolin formed from plagioclase is ubiquitous in the upper, 
weathered portions of the pegmatites, where it forms compact masses that are white except where stained 
by limonite or manganese oxides. In general the water table is the downward limit of effective kaolinization 



Feldspar Deposits of the Bryson City District, North Carolina 



41 






in the district, but kaolin is reported at depths 100 feet or more below water level at the Swain mine. Limon- 
ite is widespread as a coating along fracture surfaces of feldspars or as a pulverulent product of the weath- 
ering of biotite, garnet, magnetite, or pyrite. Manganese oxides are spottily distributed. Spots of manganese 
oxides in most places problaly record the former presence of garnet. 



ORIGIN OF THE PEGMATITES 

General statement. — For a recent review of the voluminous literature on the origin of pegmatites the 
reader is referred to the report by the author and others. 41 The present report is essentially a summary of 
field observations, and only such comments are offered as seem justified at the current stage of the investi- 
gation. 



Mineral 


STAGES OF PEGMATITE DEVELOPMENT 


Formation 

of outer 

zones 


Formation 

of inner 

zones 


Formation of 
quartz and 

quartz-feld- 
spar fracture 
fillings 


Formation of 
latest frac- 
ture fillings 
and replace- 
ment bodies 


Quartz 






















Perthite 









Plagioclasel feL^. ^ _ 


— 


? — ? 


Biotite 


—?— ? 




?<mmm 










Muscovite 


















Magnetite 













Garnet 








? 








Tourmaline 




- 






Allanite 




- 






Beryl 




• 






Pyrite 








— 


Fluorite 








— 


Galena 








— 


Thulite 








— 


Chlorite 








— 



Figure 12. Sequence of Mineral Development in Pegmatites of the Bryson City District. 



Mode of emplacement.— -Most of the pegmatites of the Bryson City district appear to be fillings of frac- 
tures caused by deformation of the region after the development of the granitic complex. There is little 
indication of forceful injection of the pegmatitic fluids; permissive injection consequent upon dilation ap- 



Cameron, E. N., Jahns, R. H., McNair, A. H., and Page, L. R., The internal structure of granitic pegmatites: Econ. Geology, Mon. 
2, 113 pp., 1949. 



42 Feldspar Deposits of the Bryson City District, North Carolina 

pears adequate to account for the relationships observed. Fractures, faults in part, that are related to south- 
westerly plunging asymmetric folds appear to have controlled the emplacement of some of the larger peg- 
matites of the border gneiss belt along the western margin of the granitic complex. Pegmatitic material 
has been produced in small part by soaking, recrystallization, and partial digestion of wall rocks, but there 
is no reason to believe that these processes account for the presence of the larger bodies, for too many of 
the pegmatite bodies of the district occupy sharply defined chambers obviously produced by fracturing. 

Although it is possible that the pegmatite bodies represent a late stage in a long-continued sequence of 
events leading to the development of the granitic complex, there is little evidence, beyond geographical asso- 
ciation, that the relationship is one of parent to offspring. A complicated sequence of events separates the 
development of the main part of the granitic complex from the development of the pegmatites. The concen- 
tration of productive pegmatites along the northwest margin of the granitic complex appears to be more a 
matter of structural control by a favorable horizon than a strict genetic relation. Pegmatites occur widely 
over the region southeast of the Bryson City area ; and from the data at hand it seems dubious that the com- 
plex at Bryson City is the true focus of a pegmatite swarm. Northwest of the complex, pegmatites appar- 
ently die out within a short distance, and their disappearance appears to coincide with a decline in the 
metamorphic rank of the metasedimentary rocks. The relationships are an intriguing problem, but there 
seems little to be gained by indulging in speculation until more is known of the regional geology. 

Sequence of mineral formation. — Tentative conclusions as to the sequence of mineral formation in the 
pegmatites are summarized in figure 12. In determining relative ages of the minerals three criteria have 
been used : peseudomorphs, vein relationships, and position in the zonal sequence. The first two criteria need 
no comment. They have been widely applied and their reliability, provided proper precautions are observed, 
is not seriously questioned. The third criterion requires comment and, indeed, defense. Its use rests on the 
premise that the order in which the zones occur, from the walls of the pegmatites inward to the cores, is the 
chronological order of formation of the zones ; that in the absence of evidence to the contrary the presence 
of a mineral within a zone indicates that it formed contemporaneously with the zone; and that fracture-fill- 
ings and replacement bodies have developed in general after the zones. The evidence for the development of 
zones from the walls inward to the core in zoned pegmatites in general 42 is reviewed only briefly here with 
comments on the portion of the evidence applicable to the Bryson City area. 

The main features of zoned pegmatites in general that point to development of zones from the walls 
inward are as follows : 

1. The material composing an inner zone may transect an outer zone or replace any part of 
the outer zone. The reverse is not true. In the Bryson City district, at least one fracture-filling is 
known to be an offshoot of the core of a pegmatite. Other fracture-fillings cutting outer zones have 
the composition of inner zones. Fracture-fillings cutting inner zones and comparable in composition 
to outer zones have not been found. 

2. Zoned pegmatites show definite sequences of mineral assemblages from the walls inward to 
the cores, and the general sequence of dominant mineral assemblages is the same for a number of 
districts. It seems unlikely that so consistent a sequence would be found if zones are formed from a 
body of liquid in any other way than by successive deposition of contrasting layers inward from the 
walls. This general sequence is applicable, with the minor exception noted above, to the pegma- 
tites of the Bryson City district. 

3. In some pegmatites, systematic variations in the compositions of certain minerals from zone 
to zone inward toward the core have been observed. In plagioclase the anorthite content decreases 
inward, in beryl the alkali content increases, in micas the lithia content increases. On the assump- 
tion that pegmatite development proceeds with falling temperature, these variations suggest that 
the zones developed inward from the walls. The reverse variation has not been found. The valid- 
ity of this generalization cannot be verified for the Bryson City district pending laboratory studies, 
but no contrary evidence has been noted. 



12 Cameron, E. N., Jahns, R. H., McNair, A. H., and Page, L. R., op cit., (Mon. 2). 



Feldspar Deposits of the Bryson City District, North Carolina 



43 



4. Minerals of inner zones may replace minerals of outer zones, but the reverse has not been 
found. This generalization likewise needs laboratory study before it can be applied to the Bryson 
City district. 

Inasmuch as the validity of these arguments for the pegmatites of the district can only be partly veri- 
fied, the paragenetic sequence given in the table is tentative and subject to revision. Their use actually 
rests on basic similarities between the pegmatites of the Bryson City district and those that have been more 
fully studied, in other districts. Study of the mutual relationships of quartz and the feldspars, including the 
mode of development of the graphic intergrowths, is particularly needed. Much work remains to be done 
before the picture of the development of pegmatite zones in the area can be considered complete. 

The fracture-fillings occupy structures that transect zonal structure and are clearly products of a late 
stage of development. In part they are contemporaneous with the cores of the pegmatites, in part they form- 
ed after the cores or at least after the core segments exposed at the present itme. Replacement bodies, al- 
bite and muscovite, were formed at some stage after the development of quartz-perthite zones, for a small 
fraction of the perthite in these zones have been replaced. The time of the replacement relative to the time 
of development of the quartz cores is not definitely known. 

In summary, available evidence indicates that the pegmatites of the Bryson City district were formed 
in two main stages : an earlier stage during which the zonal structure was developed, and a later slightly 
overlapping stage during which fracture-fillings and replacement bodies were formed. The first stage is 
quantitatively much the more important of the two, as in most districts in this country in which pegmaties 
have been mapped and studied in detail. 

MINERAL DEPOSITS 



FELDSPAR DEPOSITS 

General statement. — Feldspar deposits are scattered widely over the Bryson City area, but most of them 
are small and offer little encouragement to prospecting and development. Prospecting has been focussed 
primarily on pegmatites located during the earlier period of kaolin mining. The principal known deposits, 
including the five that have yielded the bulk of the feldspar produced, lie along the northwest margin of the 
granitic complex between Deep Creek and Sherrill Gap. 

Kinds of feldspar. — In common with most granitic pegmatites, those of th,e Bryson City area contain 
two groups of feldspars: perthite (potash-soda feldspar) and plagioclase (soda-lime feldspar). Table 2 
gives the theoretical compositions of important feldspars of the two groups. 

Table 2. Theoretical Compositions of Feldspar Minerals 





Formula 


Composition, in percent 


Name 


SiO 2 


A1 2 3 


K 2 


Na 2 


CaO 


Microcline 


KAlSi 3 8 

NaAlSi 3 8 

CaAl 2 Si 2 8 


64.7 
68.7 
43.2 


18.4 
19.5 
36.7 


16.9 






Albite* 


11.8 




Anorthite* 




20.1 











* Natural plagioclase feldspars form a series ranging in composition from pure albite to pure anorthite. 

Perthite is an intergrowth of microcline feldspar with albite. Albite is the subordinate component, oc- 
curring as thin parallel to subparallel lenses and lamellae in the microcline. In some specimens the lamel- 
lae are of microscopic dimensions, in others lamellae an inch or longer and 1/20 inch thick are found. The 
lamellae in most specimens are large enough to be visible under a hand lens or even to the unaided eye. 

The presence of a fine, cross-hatched pattern of lines, visible between the albite lamellae on cleavage 
surfaces of many samples, assists in distinguishing perthite from plagioclase. Perthite is commonly white, 
cream-colored, or light buff, but greenish, red-brown, or pink tints are shown by specimens from some of 
the pegmatites. Fresh, unweathered feldspar is hard and has a glossy luster. Weathered specimens are dull 



44 Feldspar Deposits of the Bryson City District, North Carolina 

and softer, and specimens in an advanced stage of weathering may crumble easily under light pressure. 
Such specimens are actually mechanical mixtures of relatively unaltered microcline with kaolin derived from 
the plagioclase. Watts' term 43 "semikaolinized feldspar" apparently refers to this weathered perthite. 
Watts comments (p. 59) that "semikaolinized feldspar is peculiar in that in 16 such deposits sampled, no 
semikaolinized soda feldspar was found, every deposit being potash feldspar with a maximum soda content of 
1.11 percent." He concluded that the material is higher in potash and alumina than associated fully kaolin- 
ized bands. Watts seems not to have recognized the derivation of "semikaolinized feldspar" from perthite. 

Brown limonite stain along cleavages and fractures is a common feature of perthite from weathered 
parts of pegmatites. Feldspar from some pegmatites is pink on outer surfaces but shows the common white 
to light-buff color on freshly broken surfaces. 

The plagioclase group of feldspars is commonly represented in granitic pegmatites either by albite or by 
oligoclase (90-70 percent albite, 10-30 per cent anorthite), though andesine (70-50 percent albite, 30-50 per- 
cent anorthite) is found in a few districts. Preliminary optical tests on samples of plagioclase from the 
Bryson City district suggest that the prevailing species are albite and albite-oligoclase ; hence the feldspar 
is high in soda content and low in lime content. The plagioclase is commonly white; rarely, specimens are 
greenish due to minute inclusions of pyrite or gray due to disseminated minute black inclusions of unknown 
identity. Plagioclase in the weathered parts of pegmatites is entirely or almost entirely altered to clay. 

Commercial grades of feldspar. — Specifications for commercial grades of feldspar depend on the uses to 
which the feldspar is put. There are two principal categories of commercial feldspars : potash feldspar for 
use in pottery and glazes, and soda feldspar used in the glass industry. Within these categories, however, 
commercial feldspar as sold by the mills varies within wide limits. Potash feldspar of commerce is perthite, 
hence always contains a small percentage (usually about 2 percent) of soda (Na 2 0) in the form of albite. 
Soda feldspar is sodic plagioclase, commonly albite or oligoclase. 

According to Metcalf, 44 the following are specifications for standard commercial grades (in percent) : 

For pottery bodies : 

Si0 2 65 to 73 

K 2 3.5 to 12.5 

Na 2 6.5 to 1.5 

Fe 2 3 0.10 to 0.05 

For glazes : , 

Na 2 4.0 to 9.0 

For glass : 

Si0 2 64.0 to 72 

Within each category, grades are established as follows (in percent) : . 
No. 1 grade : 

Free silica (quartz) maximum 6 

CaO .maximum 2 

No. 2 grade: 

A1 2 3 minimum 17 

Na 2 plus K 2 minimum 11.5 

Fe 2 3 maximum 0.1 

Feldspar for pottery and glazes must be ground to 99 percent minus 200-mesh. Feldspar for glass mak- 
ing must be ground to minus 20 mesh, and 42 to 85 percent must be plus 200-mesh. 

Feldspar for pottery is mixed with clay because it serves as a bonding and fluxing agent. High-potash 
feldspar has generally been preferred, but soda feldspar has been used to some extent. In glass making, 
feldspar is added to the melt chiefly as a source of alumina, which increases the resistance of the glass to 



Watts. A. S., Mining and treatment of feldspar and kaolin in the southern Appalachian region: U. S. Bur. Mines Bull. 53, pp. 

58 ff., 1913. 

Metcalf, R. W., Marketing feldspar: U. S. Bur. Mines Inf. Circ. 7184, 13 pp., 1941. 



Feldspar Deposits of the Bryson City District, North Carolina 45 

thermal and physical shock. Soda feldspars are preferred for glass making because they give a lower 
fusion temperature, lower viscosity of the melt, and longer firing range. 

A special application of feldspar is its use as the abrasive ingredient in scouring soaps and powders. 
Feldspar for this purpose must be free of quartz and must grind to a pure white color. Either soda or pot- 
ash feldspar is suitable, but as few pegmatites yield sizable amounts of quartz-free soda feldspar separable 
by hand, most feldspar for cleansers is potash feldspar. 

Mining and preparation for market. — Pegmatite mining in the past traditionally has consisted of a num- 
ber of scattered, small operations employing simple methods. In the Bryson City district the rock is drilled 
for blasting by use of pneumatic drills, and the broken rock is handsorted into waste and various grades of 
commercial feldspar on the floor of the working. Every effort is made in handsorting, within limits imposed 
by cost, to reduce the content of free quartz and deleterious impurities. The latter consist essentially of 
micas, garnet, and magnetite, all of which carry iron and are undesirable in other ways. Pieces containing 
excess intergrown quartz are discarded. Graphic intergrowths of quartz and feldspar are saved, however, 
provided the mine has a market for No. 2 feldspar, as the intergrowths fall within the limits set by the com- 
mercial standards for free quartz in feldspar of this grade. 

At the mines supplying ceramic feldspar no attempt is made to maintain a chemical control over the 
product. Separation into grades is made on the basis of experience, checked by analyses of shipments re- 
ported from the mills. The crude feldspar is crushed at the mills, analyses of batches are made, and batches 
from various storage bins are blended to obtain the products specified by the consumer. 

Feldspar and waste rock are hoisted from the mines by aerial tramway and skip or by derrick hoist. At 
the Swain mine both a derrick hoist and an inclined rail haulageway were used at different stages of opera- 
tion. Most of the feldspar recovered has been shipped to mills at Spruce Pine, N. C, chiefly by rail but partly 
by trucks. The cost of trucking from the mine to the railroad at Bryson City was reported in 1946 to be 
about $.60 per ton, the freight rate to Spruce Pine $2.03 per ton, and the cost of trucking from railroad to 
mill at Spruce Pine another $.60 per ton, or a total shipping charge of $3.23 per ton. Prices paid by various 
mills for feldspar delivered. at Spruce Pine are reported to range from $7.00 to $8.00 per long ton. Because 
of the high shipping costs, most feldspar shipped from the Bryson City district until 1946 for ceramic use 
was of No. 1 grade, because No. 2 feldspar could not be sold at a profit in the open market in competition 
with feldspar produced in the Spruce Pine district. In 1946, the Interstate Feldspar Corp. established a 
mill at Dillsboro, and in 1947 this mill was grinding No. 2 feldspar for the glass trade. In January 1949, 
No. 1 potash feldspar ground to 200 mesh was quoted in Engineering and Mining Journal at $18.50 per ton. 
Glass feldspar, white, 20-mesh, No. 1 grade, was quoted at $11.75 to $12.50 per ton. 

. Types of feldspar deposits. — Feldspar mined in the Bryson City area has come almost entirely from three 
of the mineral assemblages listed in table 1 (ms. p. 90) : plagioclase-quartz-perthite pegmatite, perthite-quartz 
pegmatite, and perthite-plagioclase-quartz pegmatite. Plagioclase-quartz-perthite pegmatite forms the bulk 
of many pegmatites and, because wall zones composed of plagioclase-quartz pegmatite are thin, may extend 
nearly to the pegmatite walls. Most of the material of this assemblage is too heavily intergrown with quartz 
to yield feldspar even of No. 2 grade. In a few pegmatites, however, this assemblage is represented by two 
zones, an outer zone of worthless material, an inner zone composed largely of graphic intergrowths of feld- 
spars and quartz with subordinate to minor perthite and plagioclase free of quartz. Zones of this type occur 
in the Deep Creek No. 1 pegmatite (not mapped separately) , in the Cox No. 1 pegmatite, and in the Carson 
south pegmatite. Material from these zones has been recovered for glass feldspar. 

Perthite-quartz pegmatite is represented by two types of zones, both occurring as inner intermediate 
zones. One type is exemplified by the perthite-quartz zone of the north McCracken pegmatite in which a 
large proportion of the perthite occurs as graphic intergrowths with quartz. This material would yield a 
superior No. 2 feldspar. The second type, represented in the Cox No. 1, the Deep Creek No. 1, the Swain, 
and other pegmatites, consists of large quartz-free perthite crystals with interstitial massive quartz. The 
feldspar is easily separated by hand from quartz, and this type of zone has yielded all but a very small per- 
centage of the feldspar of No. 1 grade produced in the district, including all the feldspar suitable for use in 
cleansers. As the ratio of perthite to quartz in these zones is high, the yield per ton of rock mined also is 
high. 



46 Feldspar Deposits of the Bryson City District, North Carolina 

Perthite-plagioclase-quartz zones, where present, occupy the same position in the pegmatite as that nor- 
mally occupied by perthite-quartz zones and likewise yield feldspar of No. 1 grade. The only zone of this 
kind that has been productive is the core-margin zone of the Carson south pegmatite. Feldspar produced 
from this zone by the Blue Ridge Mining Co. was sold for ceramic purposes, but that produced by the White- 
hall Co. has been used for cleansers. 

All three types of mineral assemblages from which commercial feldspar has been produced form inner 
zones of the pegmatites. In pegmatites or parts of pegmatites in which a quartz core, a quartz-perthite 
zone, or both, are present, any productive zones will be between the core and the outer zones. In pegmatites 
or parts of pegmatites in which a quartz core and quartz-perthite zone are lacking, the productive zones are 
the innermost zones. In tabular pegmatites these zones will be at or very near the midportion of the peg- 
matite. In large, irregular bodies, the innermost zones commonly lie between the hanging wall and the 
geometric center of the pegmatite. 

The fact that minable feldspar is restricted to inner zones is an important consideration in locating 
feldspar, for experience in this and other pegmatite districts indicates that inner zones are commonly thick- 
est and best developed in the thickets part or parts of a pegmatite. This relationship is clearly shown in 
plans of the Cox No. 1 and Deep Creek No. 1 pegmatites (figs. 7 and 8). In the Cox No. 1 pegmatite, for 
example, the inner zones are discontinuous, reaching maximum development in the broad irregular bulge 
near the center of the pegmatite. In the Deep Creek No. 1 pegmatite there are three westward bulges of 
the hanging wall (west wall) of the pegmatite; the inner zones are confined to these bulges. In the Swain 
pegmatite (pi. 8) the productive perthite-quartz zone is confined to the bulbous northerly portion of the 
pegmatite. 

Recommendations for feldspar prospecting. — The present study indicates that prospecting for feldspar 
in the Bryson City district is a fourfold problem. First, a pegmatite large enough to contain sizable inner 
zones must be located ; second, the shape of the pegmatite, particularly the positions of the thick portions, 
must be found ; third, the inner zones must be located within the thick portions ; and fourth, the dip, strike, 
and plunge of the pegmatite and of the potentially productive inner zones must be determined. 

Ordinarily, the size and shape of a pegmatite can be determined together. In the Bryson City district, 
the limits of the pegmatite at the surface are seldom indicated by outcrops or by float, but the limits can 
be found rapidly and cheaply, where overburden is not too heavy, by bulldozing or by postholes, pits, and 
trenches. Such methods are particularly effective because decomposed bedrock lies essentially undisturbed 
within a few feet of the surface in many parts of the area. When the thicker portions of the pegmatite 
have been discovered, trenches inward from the contacts with country rock can be used to determine the 
nature of the inner zones exposed at the present erosion level and can be used to outline the workable zones," 
if such are found. The first few pits and trenches should yield at least partial information as to the se- 
quence of zones within a pegmatite, and later trenches can therefore be limited to the vicinities of the pro- 
ductive zones, except as further information regarding the shape and attitude of the walls is required. Plate 
15 shows how trenches and postholes were used to outline the limits of the McCracken north pegmatite and 
the limits of the potentially productive perthite-quartz zone within it. 

Surface exploration yields valuable information regarding the potentialities of a pegmatite, but as peg- 
matites are a three-dimensional problem, such exploration is only a beginning. Productive zones are limited 
in extent in depth; they have bottoms and tops as well as ends. In a given pegmatite, erosion may not yet 
have exposed the top of the productive zone; in another, it may have reached nearly to the bottom of the 
zone or even below the bottom. Here, however, the empirical principle that inner zones are likely to be 
confined to the thicker portions of a pegmatite can assist in the search for feldspar. The contacts with wall 
rock will be exposed in determining the limits of a pegmatite. If the dips of the contacts along the sides 
of a pegmatite body are consistently toward the center of the body, the pegmatite is probably narrowing in 
depth and the bottom of the shoot is likely to be relatively near the surface. If dips are consistently away 
from the center, the pegmatite is probably thicker at depth, and there is a good chance that the surface 
exposures are either near the top of the productive zone or at least well above its bottom. 

Conclusions with regard to downward pinching or swelling in depth, however, should be made only 
if the pegmatite walls are exposed at a number of points, for mapping indicates that the walls of the pegma- 



Feldspar Deposits of the Bryson City District, North Carolina 47 

tites within the district are irregular, that local reversals of dip are not uncommon, and that the walls of 
some pegmatites vary markedly in strike and dip within short distances. The plunge of rolls of pegmatite 
walls and minor structural features of the wall rocks can be used in some pegmatite districts as a guide to 
the position of the pegmatite and its productive zones at depth. However, knowledge of these features in 
the Bryson City district is not yet adequate to indicate their reliability. The larger pegmatites in the border 
gneiss belt along the northwestern margin of the granitic complex appear to have developed along west- 
ward-dipping fractures or groups of fractures trending obliquely across the belt. Observations of the few 
pegmatites that have been mined underground suggest that the plunge of a pegmatite can be roughly calcu- 
lated as the intersection between a plane including the two longer dimensions of the pegmatite (if it ap- 
proaches lenticular form) and the plane of the foliation of the border gneiss at the locality. The plunge of 
the pegmatite at the Swain mine appears to be related to the plunge of the axis of an asymmetric flexure of 
the country rocks. 

In exploring for productive inner zones care must be taken to distinguish between cores and thick 
quartz-feldspar fracture-fillings. The outline of a core reflects the shape of the pegmatite body. Any tabular 
body oblique to the walls or to the general zonal structure of a pegmatite is suspect as a probable fracture-fill- 
ing. 

If surface exploration is done with reference to the internal structure of the pegmatites of the area, a 
saving of much time and effort spent in exploring unproductive parts of pegmatites should result. The dis- 
trict shows much evidence of haphazard prospecting, some of it underground work that has been relatively 
slow and expensive. Surface exploration is rapid and cheap. It does not furnish all the information required 
by the prospector, but it should enable him to narrow the targets of exploration and also to be sure that no 
potentially productive portion of a pegmatite at the surface has been overlooked. There are too many peg- 
matites in the district that have been tested only by one or two pits or adits, with no attempt to outline the 
pegmatites or to locate the parts most likely to contain commercial feldspar. 

The same structural characteristics used to guide surface prospecting can be used to guide subsurface 
exploration by adits, or drifts, or drilling. Diamond drilling has been successfully applied in other districts 
to exploration of pegmatite deposits, both of feldspar and of other minerals, and with proper care might 
prove useful in the Bryson City district. No general statement, however, can be made as to the feasibility 
of drilling feldspar pegmatites. Each deposit must be considered separately. Detailed knowledge of the 
structure of the exposed parts of the deposit, and of the texture and mineralogy of each zone is essential. 
Much will depend on whether the potentially productive zones pass abruptly or gradually into adjacent zones. 

As indicated in figure 10, the lack of inner zones in surface exposures does not necessarily mean that 
these zones are lacking in a pegmatite. Erosion may not have bitten deeply enough to expose the inner zones 
of the body. Detection of shoots hidden in these zones is a difficult problem because the cost of subsurface 
exploration must be kept as low as possible ; the average feldspar deposit cannot support heavy exploration 
costs. The problem is essentially one of locating a hidden zone, if the zone is present, with a very limited 
amount of exploration. The writer has no panacea for this problem. It seems evident, however, that a search 
for hidden shoots should not be made unless study of a pegmatite gives some definite reason, such as indica- 
tions of marked downward increase in the thickness of the pegmatite, for suspecting the presence of a 
-potentially productive zone. Perusal of the maps and diagrams accompanying this report will indicate clear- 
ly that the odds are heavily against the prospector who conducts subsurface exploration solely out of hope 
that better rock lies below. The large number of unsuccessful prospect workings in the district is sufficient 
evidence of the truth of this statement. Systematic prospecting with reference to internal structure, how- 
ever, should materially reduce the odds, although it is not likely to reverse them. 

MICA DEPOSITS 

General statement. — There are a number of mica prospects in the Bryson City area, mostly on the south- 
eastern margin of the complex. Records of operations at these prospects are scanty, and no appreciable pro- 
duction appears to have been made ; hence only a brief description of the economic features of the deposits 
is warranted. 

The micas are a complex group of aluminum silicates characterized by a basal cleavage along which they 
can be split into thin, flexible, elastic sheets and flakes. Only two species of true mica are found in pegma- 



48 Feldspar Deposits of the Bryson City District, North Carolina 

tites of the Bryson City district : biotite, the black iron-magnesia-potash mica, and muscovite, the lighter-col- 
ored potash mica. Biotite has no uses in industry at the present time; muscovite is the principal mica of 
commerce. 

Characteristics of muscovite. — Muscovite is found in pegmatites in "books" or crystals that reach maxi- 
mum thicknesses of several inches or more and maximum breadths of a foot or more parallel to the cleavage. 
Most books have irregular outlines, but some books show part or all of the nearly hexagonal outline which 
is the characteristic crystal form of the mineral. Thin sheets of muscovite are nearly colorless, but thicker 
sheets and books generally have distinct color. Most books are more or less marred by various structural 
defects of which the following are the most common: 

Cross-fractures — cracks interrupting the sheets. 

Tanglesheet — due to intergrowth of adjacent laminae, so that the books do not split along a 
single cleavage plane without tearing. 

Reeving — sets of closely spaced parallel minute corrugations of the cleavage. Generally two 
sets of reeves are present, intersecting at angles of 60° ("A" mica) or 120° (herringbone or fishtail 
mica) . 

Ruling — sets of sharp, parallel parting planes, at angles of approximately 60° to one another 
and at an angle of approximately 67° to the cleavage plane. 

Wedge structure — wedge-like books, due to interlayering of sheets of different size, some ex- 
tending only part way across the book, so that one side of the book is thicker than the other. 

Waviness — undulations of the laminae. 

For a more complete description of the structural defects of mica, the reader should refer to the discus- 
sion by Sterrett. 45 Structural defects mar most mica books to greater or less extent, but flawless sheets can 
be obtained from parts of some books. 

In addition to structural defects, mica books from some deposits contain minute inclusions of minerals 
such as iron oxides, tourmaline, and garnet. If large, these inclusions interrupt the continuity of the cleav- 
age laminae, spoiling the sheets. If small, the mica is said to show mineral stain. Mica from the weathered 
portions of deposits may show clay stain or vegetable stain due to infiltration of matter carried by ground 
waters. 

Preparation of muscovite for market. — Mica books as they come from the mine are rifted into thin slabs. 
Slabs too marred by structural defects to yield sheet mica are set aside as scrap mica. The others are split 
into thinner sheets from which the defective parts (bench scrap) are partly trimmed (half-trim, three-quar- 
ter trim) or entirely trimmed (full trim). The final product is trimmed sheet mica. The sheets are graded 
according to size of the flawless area; standard sizes range from 1 by 1 inch and 1*4 by 1V4 inches (punch 
mica) to 6 by 8 inches. 46 Within the various grades sheet mica is further classified according to quality, 
determined by flatness and degree of staining, as clear, slightly stained, fair stained, good stained, stained, 
and heavy stained. Qualification of mica was done by eye for many years, but in recent years there has been 
a trend toward basing qualifications, at least partly, on electrical qualities as indicated by special testing 
devices. 

Prices paid for mica depend on size and quality, increasing with both. In January 1949, prices quoted 
ranged from 12 to 22 cents per pound for punch mica to $6.00 per pound for sheets 6 by 8 inches. Scrap 
mica was quoted at $25.00 or more per ton. 

Uses of Mica. — Sheet muscovite has a unique combination of luster, elasticity, tensile strength, low 
thermal conductivity, low electrical conductivity, resistance to high temperatures, and ease of fabricating due 
to its softness and ease of splitting. 47 These properties make it useful for a large variety of electrical, radio, 
and radar purposes. Chiefly it serves as an insulating medium. Ground scrap mica likewise finds many uses ; 



15 Sterrett, D. B., Mica deposits of the United States: U. S. Geol. Survey Bull. 740, pp. 11-19, 1923. 

40 For detailed specifications for grading and classification of mica, see Standard methods of test for grading and classification 
of natural mica: Am. Soc. for Testing Materials, A. S. T. M. designation D351-38 (1938). Also Amer. Soc. for Testing Materials, 
Tentative specifications for natural block mica and mica films suitable for use in fixed mica-dielectric capacitors, A. S. T. M. Des- 
ignation: D748-45T, 1947. 



Feldspar Deposits of the Bryson City District, North Carolina 49 

for example, as a filler in paint and rubber, in roofing materials, and as a lubricant. For further informa- 
tion on use, discussions by Wierum and others, by Albertson and others, and by Gwinn, 48 may be consulted. 

Mica from deposits of the Bryson City district. — Muscovite from deposits of the Bryson City district is 
nearly colorless, greenish, amber, rum, or light ruby in color. The books seen at most prospects are badly 
marred by cracks, mineral inclusions, tanglesheet, reeving, ruling, and other defects. Little sheet mica can 
be found in the dumps and the small workings. Experience has shown, however, that the quality, grades, 
and average sheet content of mica present in a pegmatite can seldom be judged from abandoned workings. 
Mr. Oscar Martin states that small amounts of sheet mica have been obtained from a few deposits on the 
southeastern side of the granitic complex. Scrap mica, probably less than 50 tons in all, also have been pro- 
duced. 

Occurrence of muscovite. — Exposures of book mica-bearing pegmatites in the district are very poor, and 
little information has been obtained as to the occurrence of sheet-bearing mica. Observations indicate how- 
ever, that the occurrence is comparable to that in the Franklin-Sylva and certain other districts. 49 In some 
pegmatites mica books apparently occur disseminated through the full widths of the bodies. In zoned pegma- 
tites mica books large enough to yield sheet mica are concentrated in one or more zones and are lacking or 
nearly lacking in others. In the Simon DeHart prospect (pi. 1, no. 34) wedge-A muscovite in books up to 
10 by 8 by 3 inches apparently occurs in a discontinuous wall zone. In the Ashe Thomas deposit (pi. 1, no. 
32) book muscovite occurs partly in the wall zone, partly along the margin of the quartz core. A small peg- 
matite body (pi. 1, no. 31) southeast of Bryson City consists of a quartz core 3 to 9 inches thick flanked by 
a book muscovite-bearing wall zone ranging from 2 to 4 inches in thickness. In the Branton pegmatite (pi. 
1, no. 21) muscovite books are concentrated along the contact of the outer intermediate zone and the core. 

Some of the small prospects scattered along the southeast margin of the granitic complex from the lati- 
tude of Arlington Church northward to the Tuckasegee River appear to have tested tabular or lenticular 
bodies of quartz, with minor amounts of plagioclase and books of muscovite. None of these deposits ap- 
pear to be of any consequence. The small prospects on the northeast side of Welch Branch apparently were 
in similar deposits. 

In pegmatites in which the distribution of book mica is related to zonal structure, exploration should 
be governed by the same principles as those discussed in connection with feldspar deposits. In mica-bearing 
pegmatites, however, attention must be paid both to wall zones and to inner zones. Wall-zone deposits of 
mica are known from a number of pegmatite districts, and in some have been richly productive. Though 
commonly more continuous and more uniform in width than inner zones, wall zones in some pegmatites are 
discontinuous or vary markedly in mica content along strike or dip. No single exposure of such a zone, there- 
fore, is an adequate guide to its content of book mica. 

KAOLIN DEPOSITS 

General statement. — Kaolin mining in the Bryson City district is apparently an industry of the past, 
owing to the discovery and development of deposits of high-grade kaolin in the Spruce Pine district and else- 
where that are much larger and lend themselves far better than pegmatite deposits to low-cost mining. The 
kaolin industry of the first twenty years of the present century is described or mentioned by J. H. Pratt, 50 H. 



" Germany is reported to have been successful in laboratory synthesis of sheet phlogopite mica during World War II, but the 
process was not developed to the commercial stage. See Tyler, P. M., Synthetic mica research, Office of Military Government 
of Germany (U. S.), FIAT. Final Rept. (April 1946). 

48 Wierum, H. F., and others, The mica industry: U. S. Tariff Comm. Rept. 130, 2d ser., p. 155, 1938. 

Albertson, J. M., and others, Mica: U. S. Tariff Comm., War Changes in Industry Series, Rept. no. 21, 89 pp., 1947. 
Gwinn, G. R., Strategic mica: IT. S. Bur. Mines Inf. Circ. 7258, p. 18, 1943. 

49 Olson, J. C, and others, Mica deposits of the Franklin-Sylva district, North Carolina: North Carolina Dept. Cons, and Devel. 
Bull. No. 49, pp. 10-13, 1946. 

Cameron, E. N., Larrabee, D. M., McNair, A. H., Page, J. J., Stewart, G. W., and Shainin, V. E., Structural and economic char- 
acteristics of New England mica deposits: Econ. Geology, vol. 40, pp. 369-393, 1945. 

50 Pratt, J. H., The mining industry in North Carolina: North Carolina Geol. and Econ. Survey, Econ. Papers Nos. 6 (1902), 8 
(1904), 9 (1905), 11 (1907), 14 (1907), 15 (1908), 23 (1911) and 49 (1919). 



50 Feldspar Deposits of the Bryson City District, North Carolina 

Ries, 51 W. S. Bayley, 52 and A. S. Watts. 53 The most comprehensive discussions are those by Watts and 
Bayley; the reports by Pratt are chiefly brief summaries of mining activity and production. The reader is 
referred to the publications listed for a detailed account of kaolin operations. The following discussion is 
restricted to new information on the occurrence of kaolin and its bearing on prospecting for feldspar. 

Occurrence of kaolin. — Most of the kaolin output was obtained from zoned pegmatites, and the internal 
structure of the pegmatites as described in previous sections of this report is therefore reflected in the oc- 
currence and distribution of the kaolin. Kaolin was formed chiefly from plagioclase ; hence the plagioclase- 
rich zones undoubtedly yielded the highest proportion of kaolin per cubic yard of material moved. The zonal 
structure of the pegmatites was not generally recognized, but the occurrence of high-grade kaolin in "bands 
or streaks" within certain pegmatites was well known, and some of the kaolin workings offer clear evidence 
of selective mining of kaolin-rich parts. 

Two members of the sequence of mineral assemblages listed in table 1 (ms. p. 90) contain kaolin-rich 
material where weathered. One is the plagioclase-quartz assemblage, No. II of the sequence, which forms 
the wall zones of many of the zoned pegmatites. This was mined from the southern part of the Cox No. 1 
pegmatite, from the Deep Creek No. 1 pegmatite, and possibly from the Swain pegmatite. The other assem- 
blage is the perthite-plagioclase-quartz assemblage, the abnormal variant of member No. IV of the sequence. 
Weathering of plagioclase-rich portions of inner zones composed of this material has resulted in bodies rich 
in massive pure kaolin. Bodies of this type were worked at the Branton mine, but operations were not con- 
fined to these two zones. At the Randall, Carson, Swain, Cox, Deep Creek No. 1, and other deposits, kaolin- 
ized plagioclase-quartz-perthite pegmatite of intermediate zones was worked, although the content of quartz 
and perthite in this material is high. Zones rich in perthite ("hardtack"), quartz and perthite, or quartz, 
were not mined ; knowledge of this has been used as an aid in feldspar prospecting. 

Experience in the district indicates that the size of an old clay working is not necessarily proportional 
to the size of the pegmatite explored. Labor was cheap at the time of kaolin mining, and by lavish use of 
it, supplemented by horse-powered dragline and scraper devices, large amounts of weathered country rock 
were moved at some mines in order to gain access to relatively small pegmatite bodies. The Woody No. 4, 
Carson No. 2, Hans, and upper Ogle workings are noteworthy examples. 

OUTLOOK FOR THE FUTURE 

The future of mining in the Bryson City area appears to depend on success in discovering additional 
deposits of No. 1 potash feldspar. With the development of processes for recovering feldspar from granites, 
syenites, and other rocks by flotation, the importance of pegmatite mines as sources of feldspar seems likely 
to decline. The Bryson City area, moreover, is under a heavy handicap of adverse freight rates to major 
milling and consuming centers. 

Prospecting for feldspar in the district thus far has been concentrated along the northwestern side of 
the granitic complex, but some work has been done at other places scattered over the granitic complex and 
along the southeastern margin. Thus far, large pegmatite bodies have been discovered almost exclusively 
along the northwestern side of the complex north of the Tuckasegee River. In an area in which pegmatite 
oodies in general are poorly exposed, an appraisal of the chances of finding additional large bodies must 
be made with caution. The writer is not greatly optimistic, but it should be pointed out that a number of 
pegmatite occurrences already known are incompletely explored, and their outlines are only partly known. 
Bodies such as the Lackey pegmatite and the Harrison T. Crisp pegmatite may be somewhat larger than 
would appear from present exposures. A few other bodies, such as the McCracken north pegmatite and 
Carson north pegmatite, would appear to warrant further systematic exploration to determine whether eco- 
nomic concentrations of feldspar are present. 



51 Ries, H., The clays of the United States east of the Mississippi River: U. S. Geol. Survey Prof. Paper 11, 298 pp., 1903. 
Bayley, W. S., in Ries, H., Bayley, W. S., and others, High-grade clays of the eastern United States: U. S. Geol. Survey Bull. 708, 
314 pp., 1922. v 

52 Bayley, W. S., The kaolins of North Carolina: North Carolina Geol. and Econ. Survey Bull. 29, 132 pp., 1925. 

53 Watts, A. S., Mining and treatment of feldspar and kaolin in the southern Appalachians: U. S. Bur. Mines Bull. 53, 170 pp., 
1913. 



Feldspar Deposits of the Bryson City District, North Carolina 51 

DESCRIPTIONS OF MINES AND PROSPECTS 

MORRIS PROSPECT 

The Morris prospect (pi. 1, no. 1) lies 1,700 feet N. 80° W. of Deep Creek Church, a few hundred feet 
inside the boundary of the Great Smoky Mountains National Park. Mr. S. W. Enloe of the Harris Clay Co., 
Spruce Pine, N. C, states that the property was prospected for clay presumably between 1910 and 1915, but 
results were disappointing. 

Workings consist of a large number of pits on the crest and west side of a low spur, and an adit that 
extends 45 feet N. 71° W. into the east side of the spur. No pegmatite is exposed in the adit. The walls of 
the pits are so slumped that little can be seen in them, and no pegmatite can be seen in place. One line of 
pits trending N. 24° W. for 105 feet along the crest of the spur apparently explored a veinlike body of quartz 
with subordinate to minor kaolinized plagioclase. Another group of excavations about 100 feet west of the 
crest of the spur consists of 6 pits spaced over a length of 150 feet, roughly along a line trending N. 10° W. 

There is no indication that any sizable body of pegmatite was discovered during prospecting. For this 
reason, and because perthite appears to be virtually lacking in the waste piles, the prospect offers little 
promise as a source of commercial feldspar. 

CARSON MINES 

General information. — The Carson mines lie 2,900 feet N. 85° W. of Deep Creek Church (pi. 1, no. 3). 
They straddle a spur that separates two branches of a small tributary of Deep Creek, and they extend across 
the valley of the small branch south of the spur. In 1946 the mines were accessible from the road along 
the west side of Deep Creek by a side road leading up the tributary. The mines are on land owned by a Mr. 
Carson of Bryson City. Mineral rights are owned by the Harris Clay Co., Spruce Pine, N. C. 

The property was formerly known as the Hill property and was originally worked for kaolin by the 
Harris Clay Co., probably around 1910. The clay was washed in a plant located on the spur below the No. 2 
working, and the product was fiumed down to the drying and pressing plant on Deep Creek. Production 
data are not available. In 1941 and 1942 the property was prospected and operated for feldspar by W. J. 
Alexander and Oscar Pittman. In 1943 the Whitehall Co. leased the mine, worked it for 4 months, then 
subleased to Oscar Pittman, who operated the mine in the latter part of 1943 and part of 1944. Production 
records of these earlier operations are not available. During part of 1944, United Feldspar and Mineral 
Corp., Spruce Pine, N. C, is said to have worked the mine on Pittman's sublease. In late 1945 and early 
1946, the Blue Ridge Mining Co., Spruce Pine, N. C, worked the property on sublease from the Whitehall 
Co. ; production was about 700 tons of No. 2 feldspar and a small tonnage of No. 1 feldspar. The Whitehall 
Co. took over the mine in July 1946 and operated until early 1949, producing 2,079 tons of No. 1 feldspar 
and 602 tons of No. 2 feldspar. Almost all mining and prospecting for feldspar has been done at the No. 3 
and No. 4 workings, and production has come mainly from the No. 4 working. 

The principal workings at the mines are 4 open cuts (pi. 5). The No. 1 working is an open cut about 
100 feet long, 40 to 60 feet wide, and 5 to 30 feet deep. The cut trends about S. 75° W. Its walls have caved 
in places, and the full depth of the working is uncertain, but at the west end of the cut the depth may have 
been as much as 50 feet at the time operations were abandoned. The No. 2 working is a heart-shaped open 
cut about 140 feet from north to south, 120 feet in maximum width from east to west, and 10 to perhaps 50 
feet in depth. The maximum depth is uncertain because the headwall has slumped. A short crosscut trench 
gives access to the east side of the open cut. Both the No. 1 and No. 2 workings are reported to have been 
made by Harris Clay Co. A shaft, now partly filled by debris, was sunk in the decomposed interbedded 
quartz-mica schists and feldspathic mica-quartzites on the spur separating the two workings. The depth of 
the shaft is 21 feet to the top of the fill. 

The No. 3 working is an open cut 90 feet long, 18 to 45 feet wide, and 5 to 40 feet deep, trending nearly 
due north. From the north end a small chamber extends from the floor to the open cut. A steep shaft sunk 
a few feet north of the headwall presumably connected downward with the chamber, but timbering con- 
cealed the actual connection at the time of examination. In early 1947, after the mine had been mapped, a 



52 Feldspar Deposits of the Bryson City District, North Carolina 

glory hole was sunk to a depth of more than 20 feet in the floor of the open cut at the north end. No work- 
able body of feldspar was discovered. 

The No. 4 working is an open cut 100 feet long, 53 feet wide, and 75 feet in maximum depth, in the bot- 
tom of the branch leading past the Woody No. 1 mine. This working has been the source of most of the feld- 
spar recovered from the Carson property and was the only property in actual operation during 1946 and 
early 1947. A derrick located at the rim of the open cut northwest of the hoist house was used to hoist 
feldspar and muck from the floor of the working. Feldspar was loaded on trucks and hauled to the railroad 
at Bryson City. No. 1 feldspar, together with No. 2 feldspar for the glass trade, has been produced from 
the mine, but the principal product at the time of investigation was No. 1 feldspar from use in scouring 
preparations. 

General description of the pegmatite bodies. — Two pegmatite bodies, designated in this report as the 
north and south pegmatites, are exposed on the Carson property. They may be connected at depth or at the 
surface in the area northeast of the No. 4 working, but the bedrock in this area is completely concealed by 
mining debris and soil. Both pegmatites are discordant bodies having complex outlines determined largely 
by fracturing of the wall rocks. Taken together, the two bodies extend across the full width of the belt of 
border gneiss. In large part the north pegmatite lies along the contact of metasedimentary rocks and bor- 
der gneiss. The southwest end of the pegmatite is entirely in border gneiss. The south pegmatite lies in 
augen gneiss, near the boundary with granitic gneiss ; a narrow body of pegmatite along the contact of bor- 
der gneiss with granitic gneiss, adjacent to the hoist house, is probably an offshoot of the south pegmatite. 

Like the Deep Creek No. 1 and No. 2 pegmatites, the Carson pegmatites lie in a sharp flexure (possibly 
faulted) of the contact of border gneiss with metasedimentary rocks. The structure involved cannot be de- 
termined fully from present exposures. 

North pegmatite. — The north pegmatite is an extremely irregular branching body exposed over an area 
approximately 400 feet long and 200 feet wide. It is roughly oval in plan, but there are a number of wedge- 
like projections of the wall rocks into the body. Exposures do not indicate the relationships of the pegma- 
tite to the wall rock clearly, but in general it is markedly discordant to wall-rock structure. It appears to 
occupy a series of interconnected fractures, chiefly in border gneiss, that are related to a sharp asymmetric 
flexure of the contact between border gneiss and overlying interbedded quartz-mica schists and feldspathic 
mica-quartzites. Large parts of the pegmatite are concealed beneath dump material, material slumped 
from the walls, and original overburden. A series of postholes and trenches dug during the present inves- 
tigation has clarified the structure of part of the body, but information is still incomplete. The contacts vary 
markedly in strike and dip within short distances ; dips in general are moderately steep to steep. 

The northernmost exposures of the pegmatite are in the No. 1 working, made during clay mining opera- 
tions. In the south wall of the working the lower part of one segment of the core of the pegmatite, consist- 
ing of fractured, glassy to sugary quartz stained by limonite along fractures, is exposed. The core has 
three prominent sets of joints, one striking N. 25° E. and dipping 15° E., a second striking N. 33° E. and 
dipping about 80° NW., and a third striking N. 35° W. and dipping about 75° SW. The keel of the core 
is apparently double ; its two parts are separated by an upward bulge of the margin of the core. Part of the 
southeastern keel has been removed by erosion. Beneath the northwestern part of the keel and along its 
northwest side, there is a prominent zone consisting of 1- to 5-foot euhedral crystals of perthite embedded in 
a matrix of massive quartz. The two minerals are present in approximately equal amounts. Books of amber 
muscovite up to 3 inches broad and 4 inches thick are sparsely scattered through the quartz-perthite zone 
and are particularly numerous along its margin against the quartz core. Scattered crystals of kaolinized 
plagioclase are present in the zone. Much of the perthite is crumbly due to weathering. The quartz-per- 
thite zone evidently extended across the cut, for similar material lies directly against the border zone of 
the pegmatite in the north wall of the open cut directly opposite. Where pegmatite is present on the north 
wall, it forms a skin not more than a few feet thick. Evidently this wall is the approximate northern end 
of the pegmatite. The attitude of the contact and the internal structure of the pegmatite suggest that the 
pegmatite plunges southward at a moderate angle. 

Outside the quartz-perthite zone in the No. 1 working, except along the central part of the north wall, 
there is a thick zone of plagioclase-quartz-perthite pegmatite with numerous graphic intergrowths of quartz 



Feldspar Deposits of the Bryson City District, North Carolina 



53 



and feldspar. Plagioclase is wholly kaolinized. In the western part of the working this zone is separated 
from the wall by a border zone i/ 2 to 1 inch thick and a wall zone 1 foot thick, both composed of kaolinized 
plagioclase and subordinate quartz. Manganese oxides and limonite stain the kaolin ; probably they record 
the former presence of accessory garnet. 

Plate 6. 




2160 



2140- 



ELEV. 




ELEV. 

r 

2180- 



2160 



2140'- 



2160'- 



2140' 



2100- 



2080- 




EXPLANATION 



Overburden and fill 



Pegmatite, undivided 



EH 

Quartz vein 



XXX 
X X 



Quartz ( core) 



4»5 



V.r 






Tl F 
IL J| 



Quartz-perthlte pegmatite 



Perthite-quartz pegmatite 



Plagioclose-perthlte -quartz pegmatite 



1>F 






Plagioclase-perthite -quartz pegmatite; 
feldspars almost entirely in graphic 
intergrowth with quartz 



Coarse to very coarse plagioclase- 
perthite-quartz pegmatite; feldspars In 
port In graphic intergrowttj with quartz 



Approximate Inferred 

Contacts of wall rock units 



Medium to coarse-grained plagioclase- 
perthlte-quartz pegmatite; feldspars in 
part in graphic intergrowth with feldspar 



Plagioclase-quartz pegmatite 



/ 



Exposed Approximate Inferred Exposed or approximate Inferred 
Contacts of pegmatite with woll rocks Contacts between pegmatite units 



20 



40 



60 



100 Feet 



CARSON MINES 

Swain County, North Carolina 
CROSS SECTIONS 



54 Feldspar Deposits of the Bryson City District, North Carolina 

In the No. 2 working the wall zone is apparently continuous along the west wall. Other exposures in 
postholes and trenches dug during the present investigation show chiefly plagioclase-quartz-perthite pegma- 
tite. Contacts of pegmatite with border gneiss were uncovered at three places, and the wall zone, 1 to 2 feet 
thick, is present at least at two. An isolated exposure in the northern part of the working (pi. 5) show very 
coarse kaolinized plagioclase in contact with massive quartz. The outline and internal structure of the 
pegmatite in the area of the working could not be determined fully, because the floor is concealed beneath 
thick debris. The pegmatite, if a single body, is evidently interrupted by a series of partings or reentrants 
of border gneiss. No indication of a sizable body of feldspar of commercial grade was found. 

The No. 3 working, or upper feldspar mine, is near the northwest end of the north pegmatite. The peg- 
matite here is distinctly zoned. The plagioclase-quartz wall zone found in the No. 1 and No. 2 workings is 
lacking along the footwall (south wall) but is present in places along the north or hanging wall and ranges 
from 1 to 2 feet in thickness. Inside the border zone along the footwall (pi. 5, and pi. 6, section B-B), there 
is a zone of medium- to coarse-grained plagioclase-perthite-quartz pegmatite about 9 feet thick in which the 
feldspars are largely in graphic intergrowth with quartz. This zone grades into a thick zone of pegmatite 
similar in composition but extremely coarse-grained, with feldspar crystals as much as 7 feet by 5 feet. Scat- 
tered bodies of quartz up to 6 feet by 2 feet occur in the zone, and perthite against them is euhedral and free 
of intergrown quartz. Single books and composite crystals of biotite occur along fractures cutting feldspar 
and quartz. In the chamber at the head of the cut, a fracture surface 5 feet by 1 foot is coated with a com- 
posite crystal of biotite consisting of parallel strips up to a foot long, an inch wide, and an inch thick. Such 
crystals occur elsewhere along several sets of fractures. 

A zone composed of very coarse blocky perthite (crystals up to 6 feet in length) and plagioclase and 
subordinate quartz is enclosed in the coarse plagioclase-perthite-quartz zone. This perthite-quartz unit is 
evidently the innermost intermediate zone of this part of the pegmatite body. In the east wall of the cut 
it ranges from 8 to 12 feet in thickness, but in the west wall it consists of two parts, each 1 to 2 feet in thick- 
ness, on either side of a quartz core segment 3 to 5 feet wide. Perthite is the dominant feldspar in this unit. 
Sparsely scattered masses of kaolin containing numerous small flakes of muscovite are derived probably by 
hydrothermal alteration of perthite to albite and muscovite, followed by alteration of albite to kaolin. 

A series of quartz veins 2 inches to 3 feet thick cuts into all zones except the zone next to the footwall. 
The veins trend north to northeast and dip steeply west or northwest. Quartz also veins shattered perthite 
along cleavage cracks and along cross-fractures. 

Prospecting thus far has failed to discover a minable body of feldspar. The inner part of the coarse 
plagioclase-quartz-perthite zone contains considerable amounts of No. 2 feldspar, partly soda feldspar, partly 
potash-soda feldspar, but plagioclase above the level of the floor of the cut is kaolinized, and yield per ton of 
rock moved would be low. The bottom of kaolinization is said to have been reached in the glory hole made 
subsequent to mapping, but as the present operators are interested primarily in No. 1 feldspar, no attempt 
has been made to determine whether the yield of No. 2 feldspar would repay mining. 

The only potential source of feldspar of No. 1 grade is the perthite-quartz zone exposed in the walls and 
heading. This zone strikes about N. 45° E. and dips about 45° NW. The glory hole was flooded when in- 
spected in April 1947 but must have passed through the underside of the zone at shallow depth. 

The perthite-quartz zone is thickest in the east wall of the working and in the northeast branch of the 
chamber, apparently thinning westward along the strike. It is not known whether the unit is anywhere suf- 
ficiently thick to repay mining, but it would seem worthwhile to strip the remaining overburden from the 
surface east of the quarry, so as to trace the perthite-quartz unit along the strike in this direction, and to 
extend the northeast branch of the chamber along the strike of the zone. The possibilities for development 
of a sizable body of perthite-quartz pegmatite at depth could be more accurately evaluated if more were 
known of the downward extent of the two wedges of country rock that nearly separate the part of the peg- 
matite body worked in the open cut from the part lying to the north. If these wedges bottom within a short 
distance of the surface, there would be a marked swelling of the pegmatite downward, and the chances of 
finding a large body of feldspar at depth would be greater than if the wedges of country rock persist or 
expand at depth. The same question of structure is involved at the west corner of the No. 2 working. The 
strip of schist separating the part of the pegmatite indicated by postholes west of the No. 2 working is nar- 



Feldspar Deposits of the Bryson City District, North Carolina 55 

row, and dips of the contacts on either side of the strip, where observed, suggest that the strip wedges out at 
no great depth. Exploratory work would be required, however, to solve these problems. In view of the pro- 
nounced irregularity of the walls of the pegmatite, surface observations are a dubious guide to conditions at 
depth. At present the north pegmatite must be regarded as of doubtful promise as a commercial source of 
feldspar. 

South pegmatite. — The No. 4 or south pegmatite, like the others, is only partly exposed. The part of it 
revealed by feldspar mining appears to be an extremely irregular pipe, with offshoots extending into the border 
gneiss along several sets of intersecting fractures. The principal fractures trend northeasterly to east- 
northeasterly and dip steep northwest to southeast. The pipe plunges west-southwest or southwest at an 
angle, estimated roughly as 20°. The irregular underside of the pipe appears to have been intersected by the 
east end of the cut at the 2,105-foot level (pi. 6) and along the west half of the north wall at the same eleva- 
tion. At the latter place the underside is characterized by irregular rolls that plunge about 35°, S. 48° W. 
The crest of the pegmatite apparently plunges beneath a border gneiss wedge that splits the pegmatite in the 
upper part of the wall of the cut. 

Contacts of the pegmatite with wall rock are commonly sharp, but border gneiss septa separating 
parallel branches of the pegmatite along the east rim have been converted to fine-grained aplite, with wisps 
of partly aplitized gneiss, for distances of 1 to 4 inches from the contacts. Slickensided, sericite-coated sur- 
faces indicate slippage along contacts at several places, but displacements are apparently negligible. The 
pegmatite has numerous joints. The most prominent set strikes N. 79°-85° E. and dips 82° S. to vertical 
(pi. 5, plan at elevation 2,115 feet) . On the north side of the cut (pi. 5, plan at elevation 2,115 feet) , an 
oblique-slip reverse fault striking N. 5° E. and dipping 32° W. intersects the contact of pegmatite and border 
gneiss. The apparent maximum displacement parallel to the dip is 1 foot. 

The pegmatite consists of 6 asymmetrically developed zones and a series of small fracture-fillings. The 
border zone is 1,4 to V2 inch thick. It is a fine-grained (1/16-1/4 inch) mixture of plagioclase and quartz, 
with minor to subordinate perthite, scattered flakes of biotite oriented subperpendicular to the contacts, 
and scattered crystals of magnetite up to 1/2 inch in diameter. The border zone is the only continuous zone 
of the pegmatite ; it envelops the main body and extends along the walls of all offshoots. Inward from the 
walls of the pegmatite the border zone grades at most places into a wall zone (plagioclase-quartz pegmatite 
of pi. 5) 6 inches to 2^2 feet thick. The wall zone is composed essentially of coarse blocky plagioclase with 
subordinate quartz and various amounts of perthite. Scattered, haphazardly oriented books of biotite (chlo- 
ritized in part) up to 3 inches long, 1^2 inches broad, and 14 inch thick, and sparsely distributed crystals of 
magnetite 1/16 to 1/2 mcn i* 1 diameter also are present. Quartz occurs in graphic intergrowth with a few 
plagioclase crystals in the wall zone of the offshoot of the main body shown in the plan at elevation 2,115 
feet. 

The wall zone is absent in the northwestern part of the working, in the vicinity of elevation 2,105 feet 
(see plan), and a unit composed of plagioclase-quartz-perthite pegmatite lies directly against the border 
zone. This unit is a coarse- to. giant-grained mixture of plagioclase, quartz, and perthite, with minor bio- 
tite and accessory small red garnet crystals. Quartz is irregularly intergrown with some of the feldspar 
crystals, but graphic intergrowths are rare. This unit forms the apparent core of the northwest offshoot of 
the main body shown on the plan at elevation 2,115 feet. Here the unit is separated from the border zone 
by the wall zone. The unit is a zone ranging from IV2 to at least 7 feet in thickness. Its known and inferred 
relations to other zones are indicated in the plans. The zone is probably the outer intermediate zone of the 
pegmatite. 

Where present, the wall zone in the remainder of the workings is directly in contact with the middle 
intermediate zone, a lithologic type without parallel in the writer's experience. This unit consists almost 
entirely of true graphic intergrowths of quartz with white plagioclase and pink perthite. Proportions of the 
two feldspars vary from place to place, but in general plagioclase is the more abundant. The feldspar crys- 
tals range from a few inches to 4 feet in maximum dimension. Much of the graphic intergrowth is on a 
minute scale. Scattered through this peculiar "graphic granite" are strips of biotite 2 to 12 inches long, V4 
to 1 inch broad, and 1/64 to 1/8 inch thick. Some of the strips are arranged in crisscross, rosette, or spray- 
like patterns. The crystals occupy sericite-coated fracture surfaces of small extent. Plagioclase adjacent 



56 Feldspar Deposits of the Bryson City District, North Carolina 

to the strips is greenish because of the development of sericite and muscovite flakes up to 1/16 inch in diam- 
eter. The alteration extends up to 3 inches from the strips. The relationship of the two feldspars in this 
zone is an intriguing problem to be given further study. 

The middle intermediate zone is separated from the border zone in some of the workings by either the 
wall zone or the outer intermediate zone. Both these zones are absent along part of the west side of the 
working in the lower levels, and the middle intermediate zone lies directly against the border zone. 

The inner intermediate zone consists of coarse to very coarse crystals of massive plagioclase and per- 
thite, with subordinate interstitial quartz. As shown in plates 5 and 6, this zone is asymmetric and varies 
markedly in thickness. The maximum thickness (measured vertically, north of the quartz zone) is probably 
about 18 feet, but the average thickness is much less. Plagioclase occurs mostly as stout crystals 4 inches 
to 1 foot in diameter ; perthite crystals range up to several feet in length. Much of the perthite is white and 
resembles plagioclase so closely that the proportions of the two minerals are in doubt. Biotite forms scat- 
tered curving books and clusters of books, up to 6 inches broad and 1 inch thick, along fractures transecting 
feldspar and quartz. Red garnet forms scattered crystals 1/16 to 1/4 inch in diameter; in a few places it 
forms clusters up to a foot in diameter. Minute crytals of pyrite and coatings of thulite(?) occur along 
fractures in plagioclase in a few places. 

The inner intermediate zone in general is thickest along the north side and the crest of the quartz core 
described below. It was discovered first near the east end of the open cut and has since been followed down- 
plunge to the west-southwest. The angle of plunge cannot be determined accurately but appears to average 
about 17°. 

The core of the pegmatite is an irregular, perhaps discontinuous, body of quartz which plunges with the 
inner intermediate zone. Most of the core has been removed, and the outlines as restored in the cross sec- 
tions (pi. 6) involve considerable inference. Scattered crystals of plagioclase are present in the core in 
places. Quartz of the core extends outward as narrow veinlets into the inner and middle intermediate zones. 
Biotite occurs along fractures cutting quartz of the core. 

At the time of mapping, two types of fracture-fillings were exposed cutting the middle intermediate 
zone in the bottom of the workings. Both are veinlets V4 inch or less in thickness and 5 to 7 feet in exposed 
length; they occur along fractures that have uneven walls. The older set, striking N. 40° W. and dipping 
80° NE., consists of veinlets of quartz with minor microcline (perthite?) and scarce magnetite. The young- 
er set, transecting the first, consists of veinlets of quartz and greenish muscovite that strike N. 70°-80° E. 
and dip 70°-80° S. 

Commercial feldspar has been produced from both the middle and inner intermediate zones, the former 
yielding No. 2 feldspar, the latter mixed soda-potash feldspar of No. 1 grade. Both feldspars are fresh and 
unweathered. The graphic granite of the middle intermediate zone is satisfactory for the glass trade, but 
some difficulty was reported in obtaining material free of biotite. The last operators were interested pri- 
marily in obtaining quartz-free feldspar for use in scouring powder, hence operations were restricted so 
far as possible to the inner intermediate zone of perthite-plagioclase-quartz pegmatite. 

Reserves of commercial feldspar remaining in the pegmatite depend largely on the downplunge extent 
of the two zones thus far productive. No exploratory data are available, and in view of the extremely irreg- 
ular form of the pegmatite no estimate of reserves is feasible at the present time. For the same reasons, 
potentialities of the various offshoots of the pegmatite cannot be assessed. It seems unlikely that any large 
amount of pegmatite will be found at the surface south or west of the present open cut. Extensions of the 
body northeastward from the cut are concealed beneath debris. 

WOODY NO. 1 MINE 

Description. — The Woody No. 1 mine is located 3,650 feet N. 84° W. of Deep Creek Church (pi. 1, no. 2), 
in the valley of the brook that flows through the lower Carson mine. In the winter of 1946-1947, the mine 
was accessible by road to the Carson mine, thence by 800 feet of foot-trail. An old road connecting the two 
mines by way of the valley was impassable. The mine is on land owned by Mr. Samuel C. Woody of Bryson 
City. Mineral rights are held by the Harris Clay Co., Spruce Pine, N. C. The Woody pegmatite was pros- 
pected by Mr. W. L. Alexander in 1941. Later in the same year the Whitehall Co. worked the deposit under 



Feldspar Deposits of the Bryson City District, North Carolina 



57 



lease and produced 171 tons of No. 1 potash feldspar. No further work had been done at the time of map- 
ping. 

Openings at the mine consist of 8 small open cuts and 3 vertical shafts (pi. 7) . The main working con- 
sists of the No. 1 shaft, an open cut 55 feet S. 74° E. of the shaft, and appended underground workings. A 
partly filled irregular chamber that may extend as much as 20 feet south from the bottom of the shaft (ap- 
proximately at elevation 2,220 feet) is connected with the open cut by a tunnel trending N. 80° W. A drift 
extends from the base of the shaft 50 feet S. 70° W. At 26 feet from the shaft, a cross-drift has been run 
9 feet into the southeast wall of the main drift, and another on a curving course has been run 22 feet into 
the northwest wall. At the intersection of the main drift and the crosscuts there is a vertical winze about 

Plate 7. - 




EXPLANATION 



Overburden end fill 



Ouorlr-perthile pegm 



Per I hite-plagioclase -quartz pegmatite 



-perlhile pegmatite 



Mica quartiite and i 



Strike ond dip of parol lei foliotion and bedding 

/ / / 



Fault, dashed where approximate 



Rim of excavation Trench 

Pojthoie showing type of rock eipoeed 



Limit of underground w 

B 

Vertical short 



Top of winie 



20 40 60 80 tOO Feel 

I I I 

Scale 
Contour Interval 5 feel 
Ootum is approximate mean sea level 
Mopped by E. N. Cameron ond A. L. Bush 
November 1946 



Dump (doshed contours) 



WOODY NO. I MINE 
Swain County, North Carolina 

GEOLOGIC MAP, PLANS, AND CROSS SECTION 



58 Feldspar Deposits of the Bryson City District, North Carolina 

17 feet deep, nearly filled with water at the time of visit. The No. 2 shaft, with collar at 2,258 feet, is 44 
feet deep ; water level is at 40 feet. At 39 feet below the collar an alcove, 6V2 feet high and of shaft width, 
extends 6 feet N. 30° W. The No. 3 shaft, 23 feet deep (by sounding) and dry, appears to be entirely in wall 
rock. Several postholes and approximately 100 feet of trench were dug during the present investigation in 
an attempt to obtain further information on the structure and composition of the pegmatite body worked on 
the property, but systematic surface prospecting was not attempted. 

Despite the considerable number of workings on the property, the pegmatite is. poorly exposed and its 
form and structural relationships are poorly indicated. It is extremely irregular in plan but has roughly 
the shape of a Y. The stem of the Y extends approximately N. 30° W. The pegmatite is enclosed in inter- 
bedded quartz-mica schists and feldspathic mica quartzites which, wherever exposed, are in an advanced 
stage of decomposition due to weathering. Contacts are sharp, consistently discordant, and notably irreg- 
ular in detail, varying markedly in strike and dip within a few feet. Scattered observations and the relation- 
ships of the underground exposures to the surface outcrops indicate that the west wall of the pegmatite dips 
west at moderate to steep angles, and that the southwest branch of the pegmatite is a westward dipping 
irregular semi-lens. The crest of the lens probably plunges west-southwest at a moderate angle. Structural 
relations in the area of the shafts are summarized on plate 7. The wall of the pegmatite is exposed else- 
where only in the No. 3 cut and in the long trench north of the main working. A short chamber into the 
headwall of the No. 3 cut shows pegmatite in contact with metasedimentary rocks, the contact striking N. 
36° E. and dipping 83° NW. Three feet below the roof of the chamber (14 feet below the surface at this 
point) both pegmatite and wall rock are truncated by two nearly horizontal landslip surfaces. The lower 
one offsets the contact 4 inches ; the hanging wall of the upper slip consists entirely of metasedimentary 
rocks, here with nearly vertical bedding that strikes about N. 45° E. Axial planes of crumples in schist 
layers strike roughly N. 69° E. and dip 23° SE., indicating that the beds are right side up. Axes of crum- 
ples plunge 9°, S. 48°W. 

In the long trench north of the main working the pegmatite is in contact with metasedimentary rocks 
that have bedding and foliation striking N. 37° E. and dipping 46° NW. The contact strikes N. 11° E. and 
dips 25° W. 

The pegmatite consists of five zones : border and wall zones of plagioclase-quartz pegmatite with vari- 
ous amounts of perthite, an outer intermediate zone of plagioclase-quartz-perthite pegmatite, an inner inter- 
mediate zone of perthite-plagioclase-quartz pegmatite, and a core of quartz. Quartz-perthite exposed on the 
slope and in the long trench north of the main workings may represent either an additional unit or a local 
variant of the perthite-plagioclase-quartz zone. 

The border zone is 1 to 2 inches thick and is composed of *4- to 1-inch grains of plagioclase, quartz, and 
perthite. It grades into the wall zone, which is 1 to IV2 feet thick and consists of plagioclase crystals V2 i ncn 
to 6 inches in diameter, quartz, and subordinate to minor perthite. This zone is indistinct and may be dis- 
continuous. It grades in turn into the outer intermediate zone, which is similar except that it is coarser, 
contains more perthite, and contains numerous graphic to irregular intergrowths of feldspars and quartz. 
Crystals of perthite, in part intergrown with quartz, range up to 8 feet by 4 feet in section. Strips of mus- 
covite, some in parallel intergrowth with biotite, range up to 10 feet long by 6 inches wide by 2 inches thick. 
Garnet forms small trapezohedral crystals and is a conspicuous accessory mineral in places. In general, the 
crystals of the zone coarsen inward; the coarsest portions of the zone are found adjacent to the inner zone 
in the lower part of the No. 1 shaft and in the drifts extending west and north from the winze in the main 
working. 

The inner intermediate zone is composed largely of massive perthite in crystals 1 foot to more than 14 
feet in length, averaging between 4 feet and 8 feet. Quartz forms interstitial masses scattered through the 
zone. Massive plagioclase, also in large crystals, is present in the zone in places and locally predominates 
over perthite. Part of the plagioclase may have formed by replacement of perthite, but relationships are 
obscured by kaolinization of plagioclase. The zone apparently ranges from a few feet to more than 16 feet 
in thickness, but its thickness can be estimated at only a few places. 

The core of the pegmatite is formed by massive quartz, against which the perthite and plagioclase of the 
inner intermediate zone are euhedral. The core is well exposed in the No. 1 working, but its extent outside 
this working is uncertain. Massive quartz exposed in the No. 5 cut and in the trench just south of it con- 






Feldspar Deposits of the Bryson City District, North Carolina 59 

tains scattered large crystals of perthite. This unit is bordered on the west by pegmatite which resembles 
the outer intermediate zone, but the material on the east is abnormally rich in very coarse perthite and 
plagioclase, partly in graphic intergrowth with quartz. The relationships involved are not fully understood. 

The internal structure of the pegmatite, particularly the structure of the inner intermediate zone and 
core of the pegmatite, is only partly indicated. In the bottom of the No. 2 shaft, and in the heading driven 
6 feet N. 30° W. from the shaft, massive quartz is exposed in contact with a layer of perthite-plagioclase- 
quartz pegmatite 2 to 3 feet thick. The quartz forms the entire floor of the heading. The contact with per- 
thite-plagioclase-quartz pegmatite is irregular but has an average strike of N. 25° E. and a dip of 45° SE. 
The perthite-plagioclase-quartz pegmatite is overlain by pegmatite of the outer intermediate zone. The re- 
lationships of the units shown here to those exposed in the main workings are not known. The massive 
quartz bodies exposed in the two workings may be parts of a continuous core. Data at hand suggest that 
the inner intermediate zone is thickest on the hanging- wall side of the quartz core exposed in the main work- 
ing, and that the thickest parts of both units plunge southwestward. 

As shown in cross section A-A' on plate 7, the pegmatite in the main adit is displaced along a series of 
minor faults that strike north to N. 57° E. and in general dip 18° to 27° E. or SE. One fault shown on plate 
5, however, is a markedly curved surface. It dips 21° E. at the shaft, becomes horizontal near the middle of 
the adit, and dips gently west near the adit mouth. Some of the faults are simple, others are fault zones up 
to 4 feet wide, consisting of closely spaced parallel slip surfaces. Limonitic clayey gouge with fragments of 
pegmatite marks most of the fault surfaces, and some of the surfaces are rudely fluted. Apparent displace- 
ments along the faults range up to 3!/2 feet. The faults, at least in part, are landslips that appear to be gov- 
erned by sheet fractures roughly parallel to the topographic surface. In the drifts leading from the winze 
the pegmatite is cut by a series of uneven, gouge-filled fractures striking in general about N. 10° E. and 
dipping l5°-20° E. Apparent displacements along these fractures are no greater than an inch or two. The 
displacements may represent landslip along preexisting sheet-fractures developed parallel to the topographic 
surface during erosional unloading. In the bottom of the No. 2 shaft, a fault of unknown displacement strik- 
ing N. 68° E. and dipping 42° NW. is offset by another fault striking N. 77° E. and dipping 25° SE. Stria- 
tions on the two surfaces suggest a strong horizontal component of motion in each case. 

In the adit at the main working, the quartz core is intersected by several sets of joints, the most prom- 
inent of which strike N. 19° W. and dip 88° E. to 83° W. 

Feldspar. — Feldspar in the Woody No. 1 pegmatite includes both potash and soda feldspars ranging 
from pure and massive to heavily intergrown with quartz. It seems evident that only potash feldspar has 
thus far been recovered, because all plagioclase exposed in the workings is either completely altered to kaolin 
or in a moderately advanced stage of kaolinization. The potash feldspar is cream to light buff where fresh, 
but fractures and cleavage surfaces are stained by limonite in many places, especially near major joints, 
shear surfaces, and faults. Most of the stain, however, is of a kind that should be lost in grinding, and the 
quality of a properly sorted product should be high. 

Plagioclase feldspar is kaolinized in all the workings that were accessible, but kaolinization is less com- 
plete in the drifts extending from the winze, which lie deeper than the other workings. This fact suggests 
that unweathered plagioclase would be found not far below this level. 

' Up to the time of mapping (1946), two factors had prevented further development of the Woody No. 1 
pegmatite. One was the failure of the workings to disclose any sizable body of No. 1 feldspar. Most of the 
production came from the perthite-quartz-plagioclase zone along the hanging-wall side of the quartz core, 
which has been followed for a distance of about 40 feet. The winze was sunk in an attempt to find the 
downward continuation of this zone. According to local report, work at the mine stopped when the bottom 
of the shoot was penetrated. 

The limited data at hand suggest that the core of the pegmatite at the level of the floor of the winze 
strikes about N. 70° E. and plunges westward at a low to moderate angle. The end of the core may be rep- 
resented in the south drift from the winze. If this is so, the extension of the perthite-plagioclase-quartz 
zone would be downplunge to the west. There is, however, no indication whether the shoot expands or con- 
tracts in thickness at depth. 



60 Feldspar Deposits op the Bryson City District, North Carolina 

The second factor retarding development is the poor condition of the ground because of the faults and 
joints described above. The main adit has partly caved and is in dangerous condition, and considerable work 
would be necessary to ensure safe access to the area around the winze. 

Mining to date has aimed at recovery of No. 1 potash feldspar. Considerable amounts of feldspar of 
No. 2 grade may be present in the pegmatite, particularly below the zone of weathering. The inner part of 
the outer intermediate zone is rich in No. 2 potash feldspar and kaolinized No. 2 soda feldspar. It also con- 
tains some No. 1 feldspar, and a width of 28 feet of this material was found east of the quartz-perthite unit 
in the trench north of the main working. Below the limit of weathering this material should yield a high 
proportion of No. 2 feldspar of better than average quality. 

There is an additional possibility that feldspar of commercial grade might be found in the part of the 
pegmatite east of the creek, especially in the vicinity of the quartz body that is exposed at two places. How- 
ever, Mr. W. J. Alexander reports that pits sunk along the margins of this body failed to disclose apprecia- 
ble amounts of feldspar. 

Further development should begin with stripping or trenching to disclose the full outlines of the pegma- 
tites at the surface and the configuration of the various zones. This information is needed as a guide to 
further underground work. 

WOODY NO. 2 PROSPECT 

The Woody No. 2 prospect (pi. 1, no. 6) lies 2,970 feet N. 49° W. of Randall cemetery, on land owned by 
Mr. Samuel C. Woody of Bryson City. Mineral rights are owned by the Harris Clay Co., Spruce Pine, N. C. 
The prospect probably was developed during the search for kaolin deposits in the period 1910-1915. The 
only workings are an open cut 64 feet in length, 25 to 50 feet in width, and 37 feet in maximum depth, and a 
small pit nearby. The cut trends N. 12° E. 

Metasedimentary rocks with bedding and foliation striking N. 55° E. and dipping 84° SE. form the 
headwall and west side of the open cut. Decomposed pegmatite is exposed in the east wall in tight contact 
with the metasedimentary rocks. The contact strikes N. 80° E. and dips 81° SE. The pegmatite shows a 
!/8- to V4- mc h border zone, an indistinct wall zone 2 feet thick composed mainly of coarse kaolinized plagio- 
clase and quartz, and an apparent core of plagioclase-quartz-perthite pegmatite. The apparent core contains 
numerous graphic intergrowths of feldspar and quartz, accessory biotite in small books and in striplike crys- 
tals, and accessory muscovite in small flakes. The materials described above were exposed by cleaning off 
the east wall of the cut. The southern part of the pegmatite and the south contact with the wall rocks were 
not exposed. The pegmatite is concealed outside the working. 

WOODY NO. 3 MINE 

The Woody No. 3 mine (pi. 1, no. 4), 3,000 feet N. 46^4 ° W. of Randall cemetery, straddles the ridge 
south of the Woody No. 1 mine. The property is owned by Mr. Samuel C. Woody of Bryson City; mineral 
rights are owned by the Harris Clay Co., Spruce Pine, N. C. The mine was probably operated between 1910 
and 1915 by the Harris Clay Co. Workings consist of an open cut about 200 feet long, 65 to 130 feet wide, 
and about 65 feet in maximum depth. The working trends roughly N. 20° E. There has been much slump- 
ing of the walls of the cut, and relationships are poorly shown. 

The working appears to have explored a series of westward-dipping lenses of pegmatite enclosed in 
interbedded quartz-mica schists and mica quartzite. All the rocks are in an advanced stage of weathering. 
One pegmatite lens about 12 feet thick is exposed for 20 feet along strike in a large slumped block on the 
west side of the open cut near the .south end. It is a medium- to coarse-grained mixture of plagioclase, 
quartz, and perthite with minor biotite. In part the plagioclase is in graphic intergrowth with quartz. The 
contact of the pegmatite with the metasedimentary rocks is irregular and discordant in detail, but the lens 
is probably broadly concordant. 

A second pegmatite body on the east side of the working near the south end was partly exposed in two 
trenches excavated during the present investigation. The pegmatite is at least 75 feet long and trends ap- 
proximately N. 30° E. It is 18 feet wide in a trench near the north end of the pegmatite. The southeast 
contact strikes N. 20° E. and dips 78° NW.; the northwest contact strikes N. 53° E. and dips 79° SE. The 



Feldspar Deposits of the Bryson City District, North Carolina 61 

attitudes of the contacts in this trench suggest that the pegmatite has a southwestward-plunging keep, but 
exposures are too limited to give proof. In a second trench 40 feet SSW., the contact strikes N. 3° W. and 
dips 28° W. The contacts are discordant; bedding and foliation of the metasedimentary rocks adjacent to 
the pegmatite strike N. 49° E. and dip 80° NW. 

The pegmatite has a border zone Vi inch thick enclosing a coarse-grained wall zone of kaolinized plagio- 
clase with a subordinate quartz minor perthite, and accessory biotite and muscovite. The wall zone is 6 
inches to l 1 /^ feet thick. The remainder of the pegmatite exposed consists of coarse to very coarse plagio- 
clase-quartz-perthite pegmatite, in which the feldspars in part form graphic to irregular intergrowths with 
quartz. 

In the west wall of the working, near the north end, decomposed pegmatite appears in slumped material. 
The pegmatite body from which this material came is probably now largely removed above the level of the 
floor of the working. It may have been either a separate pegmatite or the northern extension of the peg- 
matite exposed in the same wall near the south end of the working. 

The mine does not appear promising as a source of commercial feldspar. No large body of pegmatite 
appears to be present, nor is there any indication of a body of feldspar sufficiently free of intergrown quartz 
to yield commercial feldspar by handsorting. 

WOODY NO. 4 MINE 

The Woody No. 4 mine (pi. 1, no. 5) lies 2,730 feet N. 39° W. of Randall cemetery, straddling the crest of 
the ridge that lies south of the Woody No. 1 and Carson mines. The mine is on land owned by Mr. Samuel C. 
Woody of Bryson City; mineral rights are held by the Harris Clay Co., Spruce Pine, N. C. The main work- 
ing is an open cut roughly 150 feet long, 100 feet wide, and 55 feet in maximum depth, trending S. 25° W. 
from the crest of the ridge. A smaller open cut just over the crest on the north side of the ridge is about 25 
feet long, 18 feet wide, and 12 feet deep. It trends N. 35° E. The two cuts are connected by a shallow exca- 
vation. The mine was worked for kaolin in the early part of the century. 

The workings are in a tabular or flat-lenticular pegmatite body near the contact of the metasedimentary 
rocks with border gneiss. Structural relations of pegmatite to wall rocks are obscured by slumping of the 
walls of the cut. The pegmatite strikes between N. 3° E. and N. 12° E. and dips about 50°-55° W. The foot- 
wall of the pegmatite is border gneiss. Metasedimentary rocks form the first exposures west of the pegma- 
tite at most places, but part of the contact of border gneiss and metasedimentary rocks is exposed at one 
point in the west wall of the cut. It seems probable that the pegmatite is largely in border gneiss, but it 
trends obliquely across the strike, so that its north end intersects the contact of border gneiss and meta- 
sedimentary rocks. Three shallow trenches made during the present investigation exposed the f ootwall side 
of the pegmatite and the underlying border gneiss. The foliation of the border gneiss strikes N. 22° E. and 
dips 52° NW. In two small exposures in the trenches, the footwall of the pegmatite strikes N. 7°-23° E. and 
dips 52°-70° NW. 

At the contact with border gneiss there is a fine-grained Vs-inch border zone of plagioclase and quartz. 
This is overlain by 2^2 feet of very coarse, kaolinized blocky plagioclase, forming the wall zone, and this in 
•turn is overlain by a core of massive quartz 4 to perhaps 6 feet thick (pi. 4) . The part of the pegmatite 
above the quartz core has been removed by mining and erosion. The quartz core forms a prominent ledge 
with a westward-sloping upper surface nearly parallel to the dip of the pegmatite body. The core is ex- 
posed for 50 feet along the strike and for about 25 feet down the dip. Exposures in a third trench dug at 
the north end of the ledge of quartz suggest that the ledge is faulted off, but relations are obscure. 

The pegmatite is an interesting one, and it is unfortunate that exposures are too poor to permit satis- 
factory study. It appears to be too small to yield significant amounts of feldspar. 

RANDALL MINE 

The Randall mine (pi. 1, no. 7), also known as the Sharptop mine, lies 3,500 feet N. 46° W. of Randall 
cemetery, at the head of the branch that flows immediately north of the Swain mine. The mine is partly on 
land owned by Mr. Samuel C. Woody of Bryson City and partly on land owned by Mr. Harry Thomas, also 
of Bryson City. Mineral rights are owned by the Harris Clay Co., Spruce Pine, N. C. The mine was worked 



62 Feldspar Deposits of the Bryson City District, North Carolina 

for kaolin by the Harris Clay Co. for several years, beginning about 1907, and is reported to have been the 
most productive kaolin mine of the Bryson City district. The clay was flumed to a washing plant down the 
valley leading southeast from the mine, and thence was flumed to the drying and processing plant of the 
company on Deep Creek. 

An open cut approximately 550 feet long, 35 to 150 feet wide, and 35 to 65 feet deep was excavated. A 
series of shafts was sunk in the floor to depths reportedly as much as 75 feet. In 1940 and 1941, Messrs. W. 
J. Alexander and Oscar Pittman sank 2 shafts, each about 35 feet deep, in the floor of the cut near the north 
end. Both shafts bottomed in fill of the old clay shafts. An adit was driven 20 feet N. 61° W. into the west 
wall of the open cut near the north end, and a drift was run N. 25° E. for 5 feet from a point inside the 
mouth of the adit. A winze at the end of the drift leads to another drift that lies 6 feet below. The drift 
runs 6 feet N. 48° W. from the winze and 7 feet S. 48° E. This work disclosed no minable body of feldspar. 
In 1946 Mr. Pittman sank two shafts farther south in the pit, but again no feldspar of commercial grade was 
found. One shaft is 23 feet deep, the other about 15 feet deep. In the course of the present investigation 
the walls of the open cut at the north end and northeast corner were cleaned off so far as possible, and the 
accessible workings were briefly examined. Large blocks have slumped from the west wall of the cut, and 
most of the rest of the cut is heavily overgrown and covered with debris. The pegmatite as a whole was 
found to be too poorly exposed to warrant detailed study. The following is a description of the more salient 
features exposed. 

The pegmatite appears to be either a large lenticular body or a series of lenses trending parallel to the 
open cut (N. 15° to 20° E.) and dipping at a moderately steep angle to the west. It is enclosed in interbedded 
quartz-mica schists and micaceous feldspathic schists. Above the level of the floor of the open cut these 
rocks are in an advanced stage of weathering. The average strike of the foliation of the metasedimentary 
rocks in the west wall of the open cut is about N. 25° E., and the average dip is about 55° NW. Schist lay- 
ers are crumpled on a small scale; axes of crumples plunge 2°, N. 25° E. The west contact of the pegmatite 
with wall rock is uneven; it has an average dip of about 50° W. The east contact of the pegmatite is ex- 
posed about 70 feet south of the north end of the open cuts. It strikes N. 43° E. and dips 80° SE., cutting 
across the foliation of the metasedimentary rocks, which here strikes N. 41° E. and dips 46° SE. Two paral- 
lel pegmatite stringers just southeast of the contact may be connected with the main body along dip or along 
strike. 

In the drift the pegmatite shows a thin border zone, an, indistinct wall zone IV2 to 3 feet thick, and a third 
zone that forms the remainder of the pegmatite exposed. The wall zone is composed of medium- to coarse- 
grained plagioclase-quartz pegmatite with minor to subordinate perthite and accessory muscovite and biotite. 
The border zone is similar but fine-grained. The third zone, probably an intermediate zone, consists of 
coarse-grained to very coarse-grained plagioclase-quartz-perthite pegmatite with strip muscovite and bio- 
tite. In part the two micas occur in parallel intergrowth. Some of the feldspar crystals are free of inter- 
grown quartz, some are partly or entirely irregular or graphic intergrowths with quartz. This material 
is exposed in the north end of the cut and in at least one of the shafts. Except that it is notably richer in 
muscovite, the material strongly resembles that of the intermediate zones of the Cox, McCracken, Deep 
Creek No. 1, and other pegmatites of the district. 

No other zones can be recognized in the pegmatite at present, but from its general similarity to other 
pegmatites of the district, one would expect to find other zones within it, including one or more zones of the 
types that are productive at the feldspar mines. Furthermore, the size of the pegmatite, as indicated by the 
dimensions of the open cut and by fragmentary data regarding kaolin operations, indicates that such zones 
might contain considerable tonnages of material. The failure to find the zones suggests that either they 
have been removed by erosion or they have not yet been reached by prospecting. The outlook for further 
exploration, however, is not good. The extent of the kaolin workings, with their deep fill, is not accurately 
known, and there has been much slumping of the walls of the open cut. Further prospecting might entail 
heavy expense without yielding commensurate information regarding the over-all form of the pegmatite and 
its internal structure. It seems likely that the deposit will remain an enigma. 



Feldspar Deposits of the Bryson City District, North Carolina 63 

NO. 8 PROSPECT 

The No. 8 prospect (pi. 1, no. 8) lies 2,850 feet N. 51° W. of Randall cemetery. Ownership was not in- 
vestigated, and nothing- is known of the history of operations. The prospect consists of an adit extending 
44 feet N. 7° W. into the side of the ridge on which the Woody No. 2, No. 3, and No. 4 mines are located. From 
a point 22 feet from the portal a drift runs N. 77° E. for 20 feet and a second drift extends N. 80° W. for 
28 feet. 

The working exposes an extremely irregular pegmatite body, apparently a series of connected irregular 
lenses having a general northeast trend. The wall rocks are weathered metasedimentary rocks. A section 
along the line of the main adit would show a pegmatite with irregular pendants and upward-projecting re- 
entrants of interbedded quartzite and mica schist and numerous apparent inclusions of wall rocks. The wall 
rocks are locally injected and feldspathized. Bedding and foliation appear to have exerted the major struc- 
tural control, but contacts are sharply discordant in places. The entire pegmatite body appears to be plung- 
ing to the southwest. 

The pegmatite is a medium-grained to very coarse-grained mixture of plagioclase, perthite, and quartz, 
with minor biotite in striplike crystals. Apart from a half-inch border zone, and the presence of scattered 
pods of massive quartz 1 foot to at least 5 feet in maximum dimension, there is little indication of zonal 
structure. Against massive quartz, perthite crystals are euhedral and lack the graphic intergrowths that 
are common in both perthite and plagioclase away from the quartz bodies. All plagioclase in the pegmatite 
has been altered to kaolin. 

The prospect appears unpromising as a source of commercial feldspar. The pegmatite seems to be 
small, and much of the feldspar is heavily intergrown with quartz. 

SWAIN MINE 

General information. — The Swain mine, also known as the Deep Creek No. 2 mine, lies 2,100 feet N. 
57° W. of Randall cemetery (pi. 1, no. 9) and is reached from Bryson City by way of a dirt road leading 
northeastward from the Deep Creek No. 1 mine. The mine is on land owned by Mr. Ben Lollis of Bryson 
City. Mineral rights to the property are owned by the Harris Clay Co., Spruce Pine, N. C. The "Swain peg- 
matite was first mined for clay; the principal workings, a series of shafts now filled, probably lie south of 
the main feldspar workings. In 1940, development work by Mr. W. J. Alexander resulted in discovery of 
a sizable body of high-grade potash feldspar. The mine was operated by the Feldspar Producing Co., Spruce 
Pine, N. C, from 1940 to 1945, under sublease from Mr. Alexander. In January 1946 the mine was subleased 
to United Feldspar and Mineral Corp., operated until September 5, 1946, and then shut down because of 
caving of the headwall of the open cut. During the 6 years the mine was operated a considerable tonnage of 
high-grade feldspar was produced, and the mine is reported to rank second only to the Deep Creek No. 1 
mine in production. 

The writer is indebted to Mr. Alexander and to Mr. Oscar Pittman, superintendent of the mine during 
nearly the entire period of operation, for information on the methods and extent of mining and development, 
and to Mr. Alexander for all information on the underground workings. A plane-table map of the open 
pit, made for the U. S. Geological Survey by Mr. R. H. Jahns in June 1945, shows the main pit at an early 
stage of the final open cut mining, which followed collapse of the underground workings. The map con- 
tributed useful information on the internal structure of parts of the pegmatite then exposed. 

Development. — Exploratory work (pi. 8) consisted of 2 shafts, the Muck and Marts shafts, both filled 
and concealed beneath debris. The Muck shaft, originally 55 feet deep, is said to be on the site of an old 
clay shaft 52 feet deep. The Marts shaft, originally 35 feet deep, is said to lie at the margin of the shoot 
of high-grade feldspar later worked in the mine. Subsequent to the sinking of the two shafts, the shoot was 
discovered in the vicinity of the northeastern part of the present main open cut, where the shoot, a south- 
westward-plunging body having the shape of a somewhat flattened pipe, intersected the bedrock surface. 
An adit with portal east of the open cut at elevation 2,118 feet was then driven westward to intersect the 
shoot, and at the same time a vertical shaft (concealed at the time of mapping beneath debris on the floor 
of the open cut) was sunk in line with the adit. Just short of the shaft, drifts were run northward and 



Plate 9. 



/Subsided area 




SWAIN MINE 

Swain County, North Carolina 
SECTION ALONG LINE A-A' 



Feldspar Deposits of the Bryson City District, North Carolina 65 

southward to the limits of the feldspar shoot. A winze was sunk at the end of the north drift to elevation 
2,098 feet, and drifts run at this level to the limits of the feldspar shoot were connected with the shaft. A 
connection of the shaft with the 2,118-foot level was then made, the shaft was sunk to elevation 2,070 feet, 
and from this point an inclined raise was run upward N. 64° E., to the surface. As the workings below the 
2,070-foot level were developed, this raise was extended downward from the shaft as an inclined winze and 
became the main haulageway of the mine. Drifts on the 2,070-foot level were carried to the limits of the 
feldspar shoot. Subsequent mining developed workings down to elevation 1,847 feet, and the main incline 
was carried down approximately to elevation 1,817 feet. 

Mining was done largely by drifting, for the pegmatite zone enveloping the feldspar shoot contained a 
high proportion of kaolin formed by weathering of plagioclase, and workings were therefore kept within the 
shoot. This condition persisted to the bottom of the mine. Because of the heavy pressure of the enclosing 
unstable material and the danger of cave-ins, only a limited amount of stoping could be done. One cave-in, 
in the part of the main incline between approximately elevation 1,860 feet and elevation 1,960 feet, made it 
necessary to sink an inclined winze from the chamber above the caved portion. From the foot of the winze, 
approximately at elevation 1,847 feet, a drift was run southeastward to intersect the main incline, and the 
caved portion was sealed off by means of a bulkhead. Subsurface operations in the mine were terminated 
by collapse of the lower workings. It is reported that the area of subsidence (shown on the map plate 8 and 
in section on plate 9) was developed at this time, so that the whole mass of rock between the surface and 
the lower workings was involved in the movement. On the spur above the mine there is a prominent land- 
slip fissure (see pi. 8), and the ground between the main fissure and the head wall of the main excavation is 
much fissured. Movements along these fractures and the main fissure are reported to have attended the col- 
lapse of the lower part of the mine workings; but examination of the area suggests that these movements 
are only the latest stages of landslip involving much of the deeply weathered rock of the spur in which the 
mine is located. 

After the collapse of the workings, a bulldozer was used to cut back the spur above the upper part of 
the underground workings, and open-pit mining of the upper part of the feldspar body was undertaken. 
In September 1946, after the pit had been deepened approximately to elevation 2,075 feet, a heavy slide of 
decomposed rock from the high west wall of the excavation brought mining to a close. 

Geological relations. — The pegmatite is apparently a pipelike body that plunges about S. 60° W. at a mod- 
erate angle. In plan at the surface it occupies an irregular, rounded area about 180 feet in length and 170 
feet in width. Outside the main working its contact is inferred partly from data obtained by postholes 
dug during the present investigation, partly from information supplied by Mr. Pittman and Mr. Alexander. 
The position of the contact south and east of the main working is only a rough approximation. 

The pegmatite body extends across the belt of border gneiss. Its eastern end is enclosed in interlay- 
ered border gneiss and granitic gneiss, its main part lies in the border gneiss, and its north end is in con- 
tact with metasedimentary rocks. The huge exposure in the wall above the main pit shows that the pegma- 
tite lies near the axis of a sharp asymmetric flexure involving metasedimentary rocks and border gneiss. 
Calculation from the dips of the two limbs of this flexure suggests that the axis of the flexure plunges about 
45° to 50°, S. 60° W., roughly parallel to the plunge of the feldspar shoot. As it is probable that the plunge 
of the shoot is roughly parallel to the plunge of the pegmatite as a whole, or at least of the northern part of 
it, a definite relationship of the pegmatite to the fold axis is suggested. The pegmatite is sharply discord- 
ant to the wall-rock structure, and it seems probable that dilatant fracturing attending development of the 
fold provided the major channel along which the pegmatite was emplaced. Apart from local increase in 
feldspar content, the wall rocks adjacent to the pegmatite appear unaffected. 

All rocks exposed in and near the workings are markedly weathered and crumble readily. Plagioclase 
has been entirely altered to kaolin, in the wall rocks as well as in the pegmatite. Potash feldspar is less af- 
fected. Some is crumbly due to kaolinization of albite lamellae, but much is hard and fresh except for 
limonite stain along fractures. Biotite ranges from nearly fresh to partly decomposed. The operators state 
that kaolinization of plagioclase was complete down to the lowest levels reached by mining, extending more 
than 100 feet below water level. The depth of weathering at this mine is in marked contrast to that of the 
Deep Creek No. 1 mine, where sound rock was found in general within 50 to 75 feet of the surface. 



66 Feldspar Deposits of the Bryson City District, North Carolina 

Composition and internal structure of the pegmatite. — Seven zones and a series of fracture-fillings have 
been recognized within the Swain pegmatite : border and wall zones composed of plagioclase-quartz pegma- 
tite, two intermediate zones composed of plagioclase-quartz-perthite pegmatite, a third intermediate zone 
composed of perthite pegmatite, a core-margin zone composed of quartz-perthite pegmatite, and a core of 
quartz. Veins of quartz with minor feldspar cut the intermediate zones, and some of them extend across 
the wall and border zones and even into the wall rock. One vein exposed in June 1945 is shown on the 
map by R. H. Jahns as a direct offshoot of the quartz core. 

The border zone, 1 to 2 inches thick, is a fine-grained mixture of plagioclase, quartz, and perthite, with 
accessory biotite. The wall zone, 4 to 5 feet thick, consists of coarse blocky plagioclase, now completely al- 
tered to kaolin, with subordinate quartz and sparsely scattered crystals of perthite. It is exposed only along 
the south wall of the main pit. It grades inward into the first intermediate zone of plagioclase-quartz-per- 
thite pegmatite. This is a mixture of coarse-grained to very coarse grained plagioclase and perthite, with 
quartz and abundant accessory biotite. Plagioclase forms crystals up to 1 foot in diameter, some unevenly 
and irregularly intergrown with quartz. Graphic intergrowths are rare. Perthite forms stout anhedral 
to subhedral crystals up to 5 feet in length. Scattered masses of quartz up to 1 foot in diameter occur in the 
zone. Against them perthite is euhedral, but against the remainder of the quartz in the zone perthite is 
anhedral. Biotite occurs in books as much as 3 inches broad and 2 inches thick, in strip-shaped crystals as 
much as 1 foot long, 1 inch broad, and V2 inch thick, and in plates up to 1 foot long, 5 inches broad, and !/2 
inch thick. 

Inside the first intermediate zone is the second intermediate zone, similar in mineral composition to the 
first but characterized by even larger crystals and by abundant graphic intergrowths of plagioclase and 
quartz. Graphic intergrowths of perthite and quartz also are present as well as large striplike crystals of 
biotite. The contact between the first and second intermediate zones is distinct in the main pit, but for 
practical purposes the zones can be treated as variants of a single zone, particularly as no unit comparable 
to the first intermediate zone can be recognized outside the main pit. Pegmatite of the type that forms the 
second intermediate zone is the largest single unit within the pegmatite body at the surface; it forms the 
walls of the main adit and is exposed in the pit, trench, and postholes south of the main pit. A trench 30 
feet southeast of the south corner of the shed exposes pegmatite of this type separated from border gneiss 
only by the border zone. 

The perthite-quartz zone is the feldspar shoot and has yielded nearly all the feldspar produced from 
the mine. The zone consists of crystals of perthite as much as 10 by 10 feet in cross section, sparsely scat- 
tered stout crystals of plagioclase (kaolinized) up to 2 by 2 feet, and sparsely distributed institial masses of 
quartz up to 11/2 feet in diameter. Biotite books up to 1 foot broad and 1 inch thick are very thinly distrib- 
uted through the zone, and are as much as 2i/ 2 feet broad and 4 inches thick along the margins of the zone. 
Taken together, plagioclase, quartz, and biotite make up only a small percentage of the zone, which is re- 
markably high in perthite content. The zone has the shape of a somewhat flattened pipe, the long axis of 
which plunges approximately S. 60° W. The angle of plunge steepens from about 40° in the upper levels 
to about 50° in the lower levels. The shoot ranges in width from about 40 feet to about 100 feet. It ranges 
from about 20 feet to about 65 feet in thickness perpendicular to the axis of plunge, averaging roughly 40 
feet. In any horizontal plane passed through the shoot, the longer dimension of the shoot strikes about N. 
35°-40° E. A plane including this longer dimension and the plunge axis of the shoot would strike N. 35°-45° 
E. and dip about 73°-79° NW. 

In the upper levels the shoot consists of cream-colored perthite stained reddish to brownish by limonite 
along fracture surfaces. Mr. Pittman states that a quartz vein intersects the south edge of the shoot about 
100 feet below the original surface. This vein persists into the lowest level reached by mining, slanting 
gradually across the shoot and nearly reaching the northwest edge on the lowest level. The portion of the 
shoot southeast of this vein is reported to consist of pinkish perthite, the portion to the northwest of white 
perthite. 

The operators report that there was no indication that the shoot was pinching out in the lowest work- 
ing ; according to a rough survey of the lower workings furnished by Mr. Alexander, the length of the shoot 
(in horizontal plan) is near the maximum in the lowest level. 



Feldspar Deposits of the Bryson City District, North Carolina 67 

The remaining two zones, the quartz-perthite core-margin zone and the quartz core, were not observed 
by the writer but according to R. H. Jahns were exposed in June 1945 south of the main shaft (see pi. 8, plan 
of workings at elevation 2,122 feet). The core-margin zone, consisting of massive quartz with scattered large 
crystals of perthite, lay at one end of a small core of massive quartz. 

Fracture-fillings of quartz with accessory perthite and plagioclase cut all zones and are particularly 
numerous in the outermost intermediate zone on the north side of the main pit. They occur along several 
sets of fractures. Those observed by the writer range in thickness from fractions of an inch to 2 feet, and 
in length from a few inches to 20 feet. A few extend across the contact into border gneiss. A vein 36 feet 
long is shown on Jahns' map as a direct offshoot of the quartz core. A noteworthy feature is that a few of 
the veins are cut by plates of biotite, formed along fractures. Evidently at least a part of the biotite in the 
pegmatite was formed at a very late stage. 

The Swain pegmatite offers a remarkable example of a plunging pipelike feldspar shoot containing a 
large tonnage of feldspar. Much of the original shoot still remains in the area explored by the workings, 
and an additional tonnage, possibly as large as that mined or larger, is said to exist downplunge from the 
workings. Had the limit of weathering been reached at reasonable depth, the mine might well have become 
the most important source of feldspar in the Bryson City district. The unsound condition of the rock en- 
closing the productive shoot, and the lack of any indication that the bottom of the zone of weathering has 
been reached, are formidable obstacles to further mining. 

The feldspar produced has thus far come from the shoot at the north end of the pegmatite. Whether 
other shoots are present in the southern and western lobes of the body is an intriguing problem. No indica- 
tion of additional shoots has been observed by the operators, and experience with the unstable ground un- 
derlying the spur has discouraged further exploration, particularly as another shoot, if plunging parallel to 
the known shoot, would presumably be enclosed in similar material and subject to the same hazards. 

HARRY THOMAS MINE 

The Harry Thomas mine (pi. 1, no. 10) lies 200 feet southwest of the Swain mine on land owned by 
Mr. Harry Thomas of Bryson City. Mineral rights to the property are owned by the Harris Clay Co., 
Spruce Pine, N. C. The deposit was opened in the 1940's by Mr. Oscar Pittman, but operations were not 
carried beyond the prospecting stage. Workings consist of an open cut 60 feet long, 16 to 22 feet wide, and 
10 feet deep, leading to a curving adit 26 feet long. The roof of the adit near the north end has caved to 
the surface. 

The pegmatite (pi. 8) is a lens-shaped body that cuts across the northwestern part of the belt of border 
gneiss to the contact with metasedimentary rocks. The lens is probably about 130 feet long and is 60 feet 
in maximum width of exposure, but it is probably not more than 30 feet thick. The lens strikes about N. 
25° W. and dips about 80° SW. In the adit at the head of the open cut, it has been displaced by a gently 
dipping fault (pi. 8, section B-B') . This fault is a curved surface, and is probably a landslip with move- 
ment in an easterly direction. 

The pegmatite has an apparent core of very coarse-grained perthite-quartz pegmatite with a high con- 
tent of perthite in large crystals. On the west side and north end of this unit there is an asymmetrically 
developed zone of very coarse blocky perthite and plagioclase, with minor quartz and accessory biotite. 
These two zones are enveloped in coarse to very coarse plagioclase-quartz-perthite pegmatite, which forms 
the wall zone of the body. A thin border zone of the same composition is present. Plagioclase is entirely 
weathered to kaolin, and perthite is stained by limonite and is in part crumbly owing to kaolinization of 
albite lamellae. 

The pegmatite is evidently of small dimensions at the surface and, barring an expansion in size of 
which there is no indication, would yield no sizable tonnage of commercial feldspar. The content of com- 
mercial feldspar in the perthite-plagioclase zone, the larger of the two units originally rich in high-grade 
feldspar, has been materially reduced by kaolinization of plagioclase in the upper part of the pegmatite. 



68 



Feldspar Deposits of the Bryson City District, North Carolina 










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Feldspar Deposits of the Bryson City District, North Carolina 69 

DEEP CREEK NO. 1 MINE 

General information.— The Deep Creek No. 1 mine (pi. 1, no. 11) lies 3,200 feet N. 83i/ 2 ° W. of Randall 
cemetery, on a spur near the head of Toot Hollow Branch (pi. 2, C). The mine is easily accessible from 
Bryson City by a gravel road up Toot Hollow to the base of the spur, thence by a graveled mine access road. 
The mine was originally opened for kaolin, probably in the early 1900's. In 1935, two brothers named 
Brooks are. reported to have reopened the mine for feldspar, producing about 2,000 tons. Average recovery 
was low and operations were suspended in 1937. In April 1939, W. J. Alexander leased the property from 
the present owners, the Harris Clay Co., Spruce Pine, N. C, and Charles Thomas of Bryson City. Develop- 
ment work led to discovery, in 1940, of- the feldspar-rich shoot that has furnished the bulk of the feldspar 
mined. Later in 1940, Alexander leased the mine to the Whitehall Co., New York, N. Y., who have operat- 
ed the mine ever since. . Total production of No. 1 feldspar from 1939 to June 1949 is reported as approxi- 
mately 56,600 tons. About 2,500 tons of No. 2 feldspar also was produced in 1946-1949 from the north 
workings. In the winter of 1946-1947, No. 2 feldspar for the glass trade was recovered from the dump by 
Interstate Feldspar Corp., operating under sublease. The feldspar was trucked to the Dillsboro mill of the 
corporation for grinding. 

Workings. — The main working (pis. 10-14, incl.) is an amphitheater-shaped open cut 180 feet in length, 
140 feet in maximum width, and 95 feet in maximum depth. From the floor of the cut at elevation 2,140 
feet a glory hole leads to an open stope that extends downward S. 70° W. at an average angle of about 40° 
(pi. 13). In October 1947, the length of this working, measured along its slope, was approximately 365 feet, 
and the floor was at elevation 1,940 feet. The stope is 22 to 40 feet wide and 94 to 110 feet high. Between 
elevations 2,090 and 2,000 feet, an irregular chamber extends northward from the glory hole as much as 
80 to 90 feet. The chamber connects southwestward, around the large pillar shown in section A-A on plate 
12, with the downward extension of the main open stope. At an early stage of the operations, a drainage 
tunnel with a somewhat sinuous east-southeasterly course was run from the glory hole at the 2,093-foot 
level to the face of the hill. The mouth of this tunnel is beneath the dump, but the tunnel was still used in 
1946-1947 as an outlet for water pumped from the lower levels of the mine. Until 1946, a derrick at the lip 
of the glory hole was used to hoist feldspar and waste from the workings. An inclined cut extending from 
the east side of the glory hole, at elevation 2,100 feet, to the floor of the main open cut was subsequently 
excavated, and an inclined cableway with skip used for hoisting. The slope of the inclined cut is 35°. 

The earlier clay workings are reported to have been a pit on the south side of the present main work- 
ing and appended adits and drifts. The Brooks brothers enlarged the pit and drove an adit west-northwest 
from the point just south of the tool shed. These earlier workings were largely removed in the excavation 
of the open cut, but the ends of several tunnels and appended drifts are preserved in the west and north 
walls of the cut. Plans of these workings are given on plate 11. 

A small open cut made by Mr. Alexander south of the main working was enlarged in 1946-1947 by the 
Whitehall Co., and an open vertical shaft 17 feet by 19 feet was sunk in the floor to a depth of 47 feet. At 
9^2 feet below the collar the roof of an old drift, probably part of the clay workings, was intersected. This 
drift is 6 feet high and 4 feet wide, with a bearing of N. 72° W. It extended only 5^ feet to the northwest 
from the center of the new shaft, but extended 151/2 feet southeast, apparently connecting with a filled shaft 
immediately beyond this point. 

The middle cut, lying just north of the main cut and connected with it by a shallow crosscut trench, was 
made largely or entirely by Mr. Alexander in prospecting for feldspar. In October 1946 this cut, despite 
slumping of the walls, was 66 feet in maximum length, 52 feet in maximum width, and 40 feet in maximum 
depth. A drift 40 feet long, 7 to 9 feet wide, and 7 feet high extends N. 40° E. from the northeast side. A 
short narrow raise connects it with a short adit driven from the east face of the hill. 

The north or Branch working lies about 85 feet northeast of the middle working. In October 1946 
this working was a somewhat irregular open cut, roughly 85 feet long, 50 feet wide, and 43 feet deep along 
the west wall. 

Form and relationships of the pegmatite. — The Deep Creek No. 1 pegmatite is one of the largest pegma- 
tites in the district ; it has a length of about 490 feet and an outcrop width ranging from 40 to 210 feet. It 




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72 



Feldspar Deposits of the Bryson City District, North Carolina 



is a markedly irregular lens, the main part of which strikes N. 17° E. and dips moderately west. The foot- 
wall is poorly exposed but is apparently uneven; it strikes N. 31° E. and dips 50° to 55° NW. in the north 
working, but strikes N. 1° W. and dips 61° W. where intersected by the drainage tunnel. The hanging wall 
is markedly irregular, with pronounced westward bulges. The middle cut explores the northernmost bulge, 
the southern margin of which is denned by a wedge-shaped eastward projection of the hanging wall. A 
dikelike offshoot of the pegmatite, striking about N. 20° W. and dipping steeply southwest, extends north- 
ward across the hanging wall from a point near the west edge of the middle cut. 

Plate 14. 



ELEV. 
2220'- 



2180'- 



2140' 




210 0'- 



2060- 



2020'- 



19 80'- 






ABB' 



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Quartz vein with 
minor feldspar 



Plagioclase- perthite- 
quartz pegmatite 



*x x x 



Plagioclase-quartz pegmatite, 
with minor feldspar 



Quartz 



WA 



Border gneiss 



Quartz-perthite pegmatite 



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Mica schist and mica quartzite 



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Perthite-quartz pegmatite 



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Scale 



Exposed Approximate Inferred Exposed or approximate Inferred 
Contacts of pegmatite and wall rock Contacts between pegmatite units 



DEEP CREEK NO. I MINE 

Swain County, North Carolina 
SECTION ALONG LINE C-C 



Feldspar Deposits of the Bryson City District, North Carolina 73 

The main working is in the middle and largest bulge, which consists of two principal parts lying on 
either side of a wedge of country rock that extends southwestward part way across the bulge. The wedge 
is exposed along the north rim of the glory hole. The keel of this wedge apparently is less than 10 feet be- 
low the quarry rim; exposures in the underground workings show that the pegmatite extends beneath it. 
North of the keel the wall of the open cut shows several projections of the pegmatite into the country rock, 
and a northward offshoot of the pegmatite exposed in the shallow pit on the slope north of the rim. Parts 
of the wall, however, are inaccessible, exposures above it are poor, and details of the structure are obscure. 

The internal structure of the pegmatite and the position and extent of the chamber extending northward 
from the glory hole strongly indicate that the bulge exposed in the middle working plunges west-southwest 
and connects with the main bulge beneath the northwest part of the main open cut (pi. 12) . 

The southernmost, smallest bulge is exposed in the south working and lies at the south end of the peg- 
matite body. Its northern side is defined by a prominent reentrant of the country rock of the hanging wall. 

The pegmatite body trends obliquely across the belt of interlayered, northwestward-dipping border 
gneiss and granite gneiss, with which are associated layers of contorted biotite schist and chloritized actin- 
olite-biotite schist. From the north end of the pegmatite to the main working the hanging wall consists of 
interbedded feldspathic quartzites and mica schist; the footwall consists of border gneiss. The south end 
of the pegmatite is in granite gneiss. The main part of the pegmatite was evidently emplaced along a frac- 
ture extending roughly N. 20° E. The main bulge, however, appears to occupy an area of complex fracturing 
and faulting extending northwest from the main body, for border gneiss and metasedimentary rocks lie on 
strike from each other on opposite sides of the bulge. The spatial relations suggest that a block of meta- 
sedimentary rocks has been dropped down along at least two faults, one extending northwest through the 
western part of the main working, the other partly occupied by the offshoot of the pegmatite from the north- 
west corner of the main working. 

Contacts of pegmatite and wall rocks in general are sharp, and evidence of reaction between them is 
commonly inconspicuous or lacking. In the headwall of the south working, however, schists and granite 
gneiss along the hanging wall of the main pegmatite have been irregularly feldspathized and in places con- 
tain pegmatite layers and lenses injected along the foliation. A granite gneiss inclusion, 39 by 8 inches in 
size, in the south wall of the working is partly feldspathized. 

Other pegmatite bodies. — Southwest of the main working a short open cut and appended short adit ex- 
pose coarse-grained plagioclase-quartz-perthite pegmatite, probably part of a small pegmatite lens. The ex- 
tent of this body is only roughly inferable from float. Several small stringers and narrow dikelike bodies, 
none apparently of any great extent, were exposed in roadcuts between this pegmatite and the main pegma- 
tite in the fall of 1946, and a partly removed lens 3 feet long and 1 foot wide, passing downward into a 
stringer, is exposed west of the main pegmatite in the road that ascends the spur east and north of the 
middle working. 

Composition and internal structure. — The pegmatite consists of 6 zones. The outermost is a fine-grained 
2- to 6-inch border zone of plagioclase-quartz-perthite pegmatite with sparsely scattered flakes and thin strips 
of biotite Vs to V2 mcn m length, and scattered crystals of magnetite up to Vi inch in diameter. Garnet, in 
trapezohedral crystals up to V4 mcn m diameter, is a scarce accessory. Biotite strips in places are haphaz- 
ardly oriented, in places subperpendicular to the contact. In small part, perthite and plagioclase form 
graphic intergrowths with quartz. 

Inside the border zone is a medium- to coarse-grained wall zone that ranges from IV2 feet to perhaps 
7 feet in thickness, averaging between 2 and 3 feet. It consists of plagioclase and quartz with minor to 
subordinate perthite and accessory biotite, magnetite, and garnet. In a few places pyrite crystals 1/64 to 
V4 mcn m diameter line narrow fracture-controlled cavities an inch to 3 inches in length. The feldspars 
form crystals that are mostly an inch to a foot in diameter and range from nearly pure to heavily inter- 
grown with quartz, in part with graphic pattern. Biotite occurs in haphazardly oriented strips up to 2 inches 
long and 1 inch broad, and in books up to 5 by 2 inches by half an inch. Muscovite forms small flakes and 
fine-grained coatings along short fracture surfaces cutting feldspar and is evidently a late mineral. The 
wall zone grades outward by decrease in grain size into the border zone, and passes inward by increase in 



74 Feldspar Deposits of the Bryson City District, North Carolina 

grain size and ratio of perthite to other minerals into the outer intermediate zone. The unit is indistinct in 
places, sharply defined in others. 

The outer intermediate zone is similar to the wall zone but ranges from coarse-grained to very coarse- 
grained and has a higher average content of perthite. Plagioclase and perthite form stout crystals ranging 
from a few inches up to 8 feet in length. The smaller crystals of plagioclase are commonly massive ; the 
larger crystals are commonly graphic or irregular intergrowths with quartz. Perthite is mostly massive, 
but some crystals contain quartz in graphic intergrowth, irregular intergrowth, or both. Biotite forms strips 
up to 6 inches long, 3 inches broad, and half an inch thick, but is more common in slablike books or groups 
of books 2 to 6 inches broad and Vi to 1 inch thick. The books cut across quartz and the feldspars. Mag- 
netite and garnet, in crystals up to half an inch in diameter, occur as rare accessories. Muscovite forms 
greenish flakes and flaky coatings along short fractures in feldspar. 

The thickness of the outer intermediate zone is measurable at few places. It appears to range from 1 
foot to at least 60 feet. Inward from the walls of the pegmatite the zone shows a gradual increase in aver- 
age grain size, and the inner part in places is composed largely of 3- to 8-foot crystals of perthite, of plagio- 
clase or perthite partly or entirely in graphic intergrowth with quartz, or both. This inner part is of some 
economic importance ; it has furnished much of the No. 2 feldspar recovered from the north working. It 
forms the walls and most of the roof of the tunnel extending northward from the middle working, the walls 
of the upper part of the shaft in the south working, and the northern margin of the main perthite-quartz 
zone, next described, in the main underground working. 

Three additional units form most of the remainder of the pegmatite: the perthite-quartz middle inter- 
mediate zone, the quartz-perthite inner intermediate zone, and the quartz core. These three units, distinct 
or telescoped, form small pods scattered through the outer intermediate zone, but their main development 
is in the westward bulges of the pegmatite. They are markedly asymmetric and discontinuous. 

The perthite-quartz zone consists essentially of crystals of perthite, 1 foot to 21 feet in length and up 
to 8 feet broad, with subordinate interstitial quartz. Plagioclase in crystals up to 5 feet long is present 
everywhere in small amounts and in a very few places is more abundant than perthite. Biotite occurs as 
slablike books, in part deformed, along fractures and sets of fractures that cut the other minerals. The 
books range in diameter up to 2 feet and in thickness up to 6 inches. In places, the feldspars and quartz are 
cut by thin quartz stringers, some of which contain scattered plagioclase crystals. Flakes of muscovite, in 
places associated with pyrite, coat fractures that traverse feldspar and are commonly slickensided. In sev- 
eral places in the surface workings, perthite is partly or entirely converted to pseudomorphs of muscovite 
and plagioclase, now thoroughly kaolinized. 

The quartz-perthite zone consists of crystals of perthite, up to 8 by 5 feet, scattered through massive, 
clear gray to milky quartz. Scattered books of biotite, similar in form and occurrence to those in the per- 
thite-quartz zone, are present. Haphazardly oriented, rod-shaped aggregates of parallel tourmaline crystals 
transversely fractured and healed with quartz are scattered sparsely at intervals along the gradational 
boundary between the quartz-perthite and perthite-quartz zones. In places the tourmaline is intergrown 
with allanite. The aggregates range up to 8 inches by 3 inches in diameter, and from a few inches to more 
than 5 feet in length. Single crystals of tourmaline range up to 4 inches in diameter. They are embedded 
in quartz or in quartz and feldspars. Perthite adjacent to allanite shows the characteristic reddish dis- 
coloration indicative of radioactivity. The quartz core consists entirely of coarse, massive, gray to milky 
quartz. Its boundary against the quartz-perthite zone is drawn at the inner limit of the occurence of per- 
thite crystals. 

Plates 10 to 14, inclusive, and figure 11 show the form and relationships of the three inner zones as 
known and as inferred from present exposures and from information furnished by the operators. Material 
corresponding to one or more of these units forms scattered small pods and lenses at several places (see, for 
example, pi. 11, plan of 2,093-foot level), but the three units are mainly developed in the westward bulges of 
the pegmatite. One segment of the quartz core is exposed for 18 feet along the base of the wall of the south 
part of the middle working. On the north side of the core the perthite-quartz zone forms an irregular, west- 
ward-dipping body, up to 16 feet thick. An intervening quartz-perthite zone is too narrow to be mapped sepa- 
rately. The core evidently terminated in the cut, but the perthite-quartz zone evidently extended northeast 
across the cut, for it is exposed in the northwall and in the roadcut north of the working. The zone plunges 



Feldspar Deposits of the Bryson City District, North Carolina 75 

approximately S. 70° W. at a moderate angle; its keel therefore passes above the roof of the tunnel extend- 
ing north from the working. The point of emergence of the keel as inferred from mapping has subsequently 
been shown by bulldozer-stripping to be approximately correct. The crest of the body plunges southwest- 
ward beneath the outer intermeditte zone, which extends over its top in the west wall of the working. 

A second segment of the core in the main working is now represented only by a small remnant of mas- 
sive quartz at the southeast margin of the glory hole. According to Mr. Oscar Pittman and Mr. W. J. Alex- 
ander, the core formed a lens roughly 70 or 80 feet long and about 20 feet in maximum width. It extended 
S. 60° W. from a point that was roughly due north of the north corner of the hoist house and was within 10 
feet south of the north rim of the cableway cut. The lens projected about 20 feet above the level of the 
present floor of the main working. Its bottom probably was at no point more than 20 feet below the pres- 
ent floor of the main open cut. This lens was apparently enclosed in a segment of the quartz-perthite zone. 
A second segment of this zone occurs as an isolated body extending northwest from the northwest corner 
of the glory hole. Two segments of the perthite-quartz zone are exposed in the main working. The main 
segment originally formed a hook-shaped body that was thickest along the northwest side of the core and 
enclosing quartz-perthite zone; it extended around the keel of the quartz-perthite zone and part way along 
its footwall side. It was Mr. Alexander's discovery of this segment that established the property as a po- 
tentially productive feldspar deposit. 

Another segment of the perthite-quartz zone is exposed in the northwest part of the open cut. It ap- 
pears related to the bulge of the pegmatite north of the projecting wedge of metasedimentary rocks. The 
size of this body is unknown. It may extend farther eastward than indicated on the map. 

The main segment of the perthite-quartz zone expands in breadth and strike length below the floor of 
the main open cut. The portion of this zone lying northwest of the quartz-perthite zone has been followed 
downward and has been very productive. The shoot that it forms trends in general east-northeast, dips 
sharply north-northwest to vertical and plunges irregularly southwestward. The keel plunges at about 
40° between the 2,150-foot and 2,093-foot levels, steepens markedly between the 2,093-foot level and the 
2,020-foot level, flattens to about 32° between the latter level and elevation 1,970 feet, then steepens again 
toward the bottom of the workings. The crest of the shoot cannot be delineated fully at present, but in the 
lower workings it is apparently roughly parallel to the keel. 

On any level the perthite-quartz zone in general extends farther northeast than the quartz-perthite 
zone. In places, perhaps everywhere, it extends around the keel of the quartz-perthite zone (see plan of 
2,093-foot level, pi. 11) but is too narrow to repay mining where exposed. Whether the perthite-quartz zone 
also extends around the crest of the quartz-perthite zone is unknown. Mining has nowhere extended to the 
crests of the zones. Because the known perthite-quartz zones in pegmatites in the Bryson City district are 
best developed between the cores and the hanging walls, the prospect of discovering a workable part of the 
zone on the southeast side of the quartz-perthite zone does not appear bright, but the flank of the zone in the 
portion between keel and crest seems to offer considerable promise. 

The form of the productive part of the perthite-quartz zone is complicated by a pronounced northward 
bulge between elevations 2,093 feet and 2,000 feet. Owing to the bulge, the keelward portion of the zone" in 
the vicinity of elevation 2,040 feet reaches a width of nearly 100 feet. This expansion lies downplunge 
from the perthite-quartz zone segment exposed in the middle working. The expansion probably represents 
the junction of this segment with the segment followed downward from the floor of the main working. The 
fact that much of the roof of the underground chamber (pi. 12) is in perthite-quartz pegmatite strongly 
supports this inference. It is also possible that the perthite-quartz unit exposed in the northwest part of 
the main open cut joins the main shoot downward. If either inference is correct, a considerable tonnage of 
No. 1 feldspar remains above the roof of the underground chamber. 

The smallest of the three conspicuous bulges is exposed in the south working. The northern side of this 
bulge is formed by a wedge of granite gneiss and border gneiss that may extend even farther toward the 
footwall than inferred on the map. In October 1946, the south working was considerably smaller than 
shown on the map, which was revised in January 1947 to show the newer work. The headwall lay southeast 
of its present position, and a small open stope, 3 to 6 feet wide, extended southwest into the headwall, from 
a point about at the center of the southwest rim of the present shaft. This chamber was excavated by Mr. 



76 Feldspar Deposits of the Bryson City District, North Carolina 

Alexander in a lens of very coarse massive perthite and kaolinized plagioclase, with subordinate quartz 
and slabby books of biotite 3 to 8 inches broad and Vi to V2 mcn thick. Quartz occurred in part as masses 
interstitial to feldspar, in part in graphic intergrowth with feldspar, particularly plagioclase. This lens was 
interpreted (pi. 10) as material of the perthite-quartz zone, though differing from typical perthite-quartz 
pegmatite in that it contained graphic intergrowths of feldspar and quartz. It strongly resembles the mate- 
rial forming the outer part of the productive shoot in the main working. Mr. Alexander recovered approxi- 
mately 45 tons of No. 1 feldspar (perthite) from the working. The northern end of this lens was inter- 
sected by the shaft, but downward the proportion of graphic intergrowths increased, and at about 25 feet 
below the rim the material became noticeably poorer in perthite. It seems evident that the shaft has pene- 
trated the bottom of the lens. Probably the lens plunges in a southwesterly direction, roughly parallel to 
the plunge of the productive shoot in the main working. A drift in a direction S. 70° W. from the bottom of 
the shaft, with crosscuts perpendicular to the drift at intervals, would appear to offer the best chance for 
locating the lens. It seems unlikely, however, that a shoot of large size will be found, unless there is a 
notable downward expansion of the pegmatite. 

Small podlike bodies, mostly quartz lenses with marginal massive perthite, plagioclase, or both, are ex- 
posed in the drainage tunnel, in the roof of the north end of the tunnel in the middle working, and in the 
north working. One southwest-plunging pod in the northwest corner of the north working yielded a small 
tonnage of No. 1 feldspar. 

Quartz and quartz-feldspar veins. — Veinlike fracture-fillings of quartz, most of which contain subordi- 
nate amounts of perthite and plagioclase, are exposed in all workings, and are most numerous in the main 
and south workings. Most of these fracture-fillings are zoned, consisting of a quartz core bordered by an 
irregular discontinuous selvage of perthite or of perthite and plagioclase, the crystals of which are euhedral 
against quartz. The fracture-fillings range from an inch to 2 feet in thickness and are exposed for lengths 
as great as 40 feet. None is exposed in entirety. The most prominent set is found in the north rim of the 
glory hole and the north wall of the main open cut. These veins strike N. 55°-78° E. and dip 60°-80° NW. 
They cut all zones from the perthite-quartz zone outward, and a few extend outward into the metasedimen- 
tary rocks. The material composing these fracture-fillings is not unlike that of the quartz-perthite zone, 
but no direct connection can be established. The part of the pegmatite which would logically be expected to 
show the connections has been mined out in the sinking of the glory hole. 

Fracture-fillings in the south working strike N. 50° to 70° E. and dip 60° to 80° NW. Strikes of similar 
bodies in the middle and north working range from N. 27° W. to N. 13° E., and dips range from 59° to 67° W. 

In addition to the more regular fracture-fillings, irregular bodies of similar material form lenses, veins, 
and networks in pegmatite of the outer zones at places along the north wall of the main working. 

Feldspar. — Feldspar produced from the Deep Creek No. 1 mine has come largely from the remarkable 
plunging shoot followed by the main working. The part of the perthite-quartz zone forming this shoot 
yields, by hand sorting, a high proportion of cream, buff, or slightly greenish pure perthite. The feldspar 
is used in making cleansing powder, so care is taken to procure material free of quartz and other impurities 
that would yield particles that would be objectionable in the ground product owing to their hardness or color. 
A small percentage of pure plagioclase is present in the mine product. It is fully as desirable as perthite 
for cleansing purposes. Mining is restricted as closely as possible to the perthite-quartz zone. The percent- 
age of feldspar in the quartz-perthite zone is too low to repay mining. The innermost part of the plagio- 
clase-quartz-perthite zone forming the northern margin of the shoot contains considerable amounts of mas- 
sive perthite, so much so that the writer had difficulty at first in distinguishing it from the shoot. The 
boundary is an assay wall ; the northern limit of mining is set by a gradual rise in the proportion of waste 
to usable feldspar. 

Until the establishment of a mill at Dillsboro in 1946, no attempt was made to recover or market the 
lower grades of feldspar, but during the present investigation recovery of No. 2 feldspar was begun, partly 
from the north cut, partly from the dumps. 

Kaolin. — The upper part of the pegmatite, except in the north working, is deeply weathered. Plagioclase 
has been altered to kaolin, biotite and garnet to iron and manganese oxides. Perthite is commonly little 



Feldspar Deposits of the Bryson City District, North Carolina 77 

affected, except that kaolinization of albite lamellae has caused disintegration where weathering is most 
pronounced, and some of the perthite near the surface is reduced to a sand. Weathering extends below the 
floor of the middle and main workings, but sound rock was found in the glory hole within 20 feet of the 
floor of the main working. In the south working plagioclase is completely kaolinized at 47 feet below the 
collar. The upper kaolinized part of the pegmatite was prospected, probably by the Harris Clay Co. Clay 
workings were primarily in the outer zones. Production is unrecorded, but was probably small. 

Outlook for the future. — Future productivity of the mine depends partly on the downplunge extent of 
the main shoot, partly on the relationship of this shoot to the perthite-quartz bodies exposed in the middle 
working and in the northwest portion of the main working. Less promising possibilities are discovery of 
a shoot on the footwall side of the quartz-perthite zone in the main working, and of a workable perthite- 
quartz body downplunge from the south working. 

The downplunge extent of the main shoot is unknown. In October 1946, mapping of the 1,946-foot 
level, the bottom level at that time, suggested a shortening of the main shoot at depth, but the working was 
subsequently extended northeast for at least 20 feet without reaching the keel of the shoot. The crest lies 
beyond the southwest end of the working on this level. According to Mr. Buchanan, foreman, mining in 
this direction was discontinued because the shoot narrowed. 

If the present interpretation of the relationship between the main shoot and the shoot exposed in the 
middle working is correct, a considerable tonnage of high-grade feldspar remains between the roof of the 
large chamber and the floors of the present open cuts. Without more data on the configuration of the hang- 
ing wall in this part of the property, however, no estimate of reserves is possible. 

Drifts across the quartz-perthite zone from the main underground working would be needed in order 
to determine whether a workable shoot lies southeast of it. Drilling might serve the same purpose, but the 
materials involved are so coarse-textured that it seems unlikely that the boundaries of the shoot could be 
determined except by means of closely spaced holes. Drifting likewise seems the best means of exploration 
from the south working. 

MCCRACKEN MINES 

General information. — The McCracken mines (pi. 1, no. 12) lie 2,800 feet N. 55° E. of Sherrill Gap, near 
the headwaters of Bryson Branch. Access to the property is by improved road up the valley of Bryson 
Branch to the sharp bend a few hundred feet west of the ridge between Bryson Branch and Toot Hollow 
Branch, thence by unimproved road northward along the east side of Bryson Branch. The mines are on 
property owned by a Mr. J. McCracken of Bryson City. The earliest mining was for kaolin, presumably 
during the decade 1910 to 1920. A small amount of feldspar is reported to have been taken from the No. 3 
working in the early 1940's. The property was leased by the Blue Ridge Mining Co. in 1945, and operations 
by the company were still in progress in early 1947. About 1,500 tons of feldspar of No. 2 grade was pro- 
duced. 

Workings consist of pits, open cuts, and adits, with appended drifts and chambers (pi. 15), made dur- 
ing operations for kaolin and feldspar. In addition, a series of trenches and postholes was dug during the 
present investigation to obtain information on the form and internal structure of the pegmatite. The mine 
workings are in a series of pegmatite bodies that extends for 480 feet nearly due north. Taken as a group, 
the pegmatites trend obliquely across the strike of the wall rocks. The wall rocks are granitic gneiss at the 
southernmost workings and border gneiss in part interlayered with granitic gneiss in the middle workings. 
In the No. 1 working pegmatite lies in border gneiss but is probably within 20 feet of the contact with 
metasedimentary rocks. Foliation in the wall rocks strikes northeasterly and dips northwest at moderate 
to steep angles. 

Workings 1 to 4 (pi. 15) are in the northernmost and largest of the group of pegmatites, a westward- 
dipping lenticular body that trends a few degrees east of north but strikes roughly N. 20° W. This body 
apparently terminates northward in the north end of the No. 5 working. It lies in border gneiss, the folia- 
tion of which strikes northeast and dips northwest at moderate to steep angles. A second pegmatite body, 
apparently extending east-northeast to northeast, is exposed in the south end of the No. 5 working. It may 
connect with the northern pegmatite beneath the dump east of the working. The No. 6 working is in a 



78 Feldspar Deposits of the Bryson City District, North Carolina 

complex assemblage of interconnected pegmatite bodies enclosed in granitic gneiss, the foliation of which 
strikes N. 50° to 55° E. and dips steeply southeast to northwest. 

North pegmatite. — This pegmatite is a lenticular body 290 feet in exposed length and nearly 100 feet in 
exposed width. Structure sections suggest that its maximum thickness, which is found in the area between 
the No. 1 and No. 4 workings, is more than 75 feet. The hanging wall is exposed at 3 places, dipping 34° to 
56° W. The footwall is exposed in the No. 3 and No. 4 workings. The contact in the adit at the No. 4 work- 
ing is in part highly irregular, but at most places in the adit dips 47° SW. to 50° W. The footwall intersects 
the floor of the chamber of the No. 3 working (elevation 2,210 feet), and it is evident from this fact, from 
information supplied by the operators, and from the position of the contact at the surface as determined by 
postholes, that there is a pronounced downward roll of the footwall beneath the open cut of the No. 3 work- 
ing (pi. 15, section A- A'). The thickness of the pegmatite down dip from this working is much less than 
the width of outcrop suggests. The plunge of the pegmatite is not known. A trench made to locate the 
northern tip of the pegmatite failed to disclose the plunge, and the plunge can be inferred only on the basis 
of a series of assumptions. Like the Deep Creek pegmatite, the north McCracken pegmatite appears to 
occupy a westward-dipping fracture developed in border gneiss. The plunge of the pegmatite should there- 
fore be defined by the intersection of the plane of fracture with the belt of border gneiss. Taking the aver- 
age strike of the border gneiss as N. 40° E., its average dip as 70° NW., the strike of the pegmatite as about 
N. 20° W., and its dip as 45° W., the expectable plunge of the pegmatite would be about 45°, S. 60° W. 

Four zones have been recognized in the pegmatite: border zone, wall zone, intermediate zone, and ap- 
parent core. The border zone, half an inch to 2 inches thick, consists of fine-grained plagioclase-quartz-per- 
thite pegmatite, with accessory biotite in flakes mostly oriented perpendicular to the contact. The wall zone 
is exposed only in the No. 1 and No. 3 workings, where it is a medium-grained mixture of blocky plagioclase, 
plagioclase intergrown irregularly with subordinate quartz, and accessory biotite in striplike and slablike 
crystals up to 4 inches in maximum dimension. The zone is absent in the No. 4 and No. 5 workings. 

The bulk of the exposed pegmatite is composed of coarse to very coarse plagioclase-quartz-perthite peg- 
matite of the intermediate zone. This material consists of plagioclase and perthite in graphic to irregular 
intergrowth with quartz, blocky perthite, blocky plagioclase, and accessory biotite in large strip-shaped 
crystals and in slablike books up to 1 foot broad and 2 inches thick. The feldspars occur in stout crystals 
up to 6 feet in length. 

The apparent core of the pegmatite was exposed only in the headwall of the No. 3 working at the time 
of mapping. It is an extremely coarse-grained mixture of quartz-free perthite and graphic intergrowths of 
perthite and quartz. Crystals of feldspar in this zone are as much as 8 feet in maximum dimension. This 
zone would yield a grade of feldspar intermediate between No. 1 and No. 2. The chamber driven into the 
headwall of this working was evidently intended to intersect the down-dip extension of the zone ; but as the 
bottom of the zone is parallel to the footwall, which rolled upward at the head of the open cut, the chamber 
apparently passed under the shoot and is mostly in pegmatite of the intermediate zone. Trenches dug dur- 
ing the present investigation served to delimit the zone at the bedrock surface, but no subsurface exploration 
could be attempted. In order to determine whether the shoot persisted at depth in the southern part of the 
pegmatite, the operators in February and March 1947 drove a crosscut from the inner end of the No. 3 work- 
ing. The crosscut was run 50 feet N. 84° W., without reaching the west contact of the pegmatite. At 10 
to 26 feet from the adit material was intersected that was richer in perthite than usual in the intermediate 
zone, but higher in plagioclase than the shoot. It is not certain that this material represents the downward 
continuation of the shoot. Cross section A- A' on plate 15 shows that the pegmatite probably narrows 
abruptly downward, but it is not proven that either the pegmatite or the apparent core pinches out within 
a short distance of the surface. Further exploratory work is needed to determine the potentialities of the 
pegmatite. The logical procedure would be to extend the adit of the No. 3 working to the latitude of the 
No. 1 working, with cross drifts perpendicular to the strike of the pegmatite. In this way, the possibility 
that both pegmatite and shoot plunge west or even north-northwest would not be overlooked. 

In the eastern of the two short adits into the headwall of the No. 1 working there is an irregular body of 
massive quartz about 5 feet long and 21/2 feet in maximum width. Around this body is a mantle of blocky 
perthite and plagioclase in coarse crystals that project into the quartz and are euhedral against it. Plagio- 



Feldspar Deposits of the Bryson City District, North Carolina 79 

clase (now kaolin) appears to have developed in part at the expense of perthite. Slablike books of biotite 
and ruled composite crystals up to IV2 feet long, 6 inches wide, and 2 inches thick occur along fractures 
transecting the boundary of the quartz body. The quartz body and its mantle are both enclosed in material 
of the intermediate zone. A roughly tabular body of quartz margined by small kaolinized plagioclase crys- 
tals is exposed in the north branch of the chamber at the No. 3 working. It appears to be a fracture-filling 
that cuts the intermediate zone. 

In the older workings and in all surface trenches, plagioclase is entirely kaolinized, and perthite is more 
or less stained brown by limonite. Plagioclase is only partly kaolinized in the western part of the crosscut 
in the No. 3 working, however, and this indicates that the bottom of the zone of weathering is not far below. 

As at other mines in the district, landslips have offset the pegmatite in places in the surface workings. 
The most prominent is the one exposed in the No. 1 working; it is shown in section A- A' on plate 15. 

Middle pegmatite. — The middle pegmatite is poorly exposed in the south part of the No. 5 working. It 
trends northeast and appears to be about 18 feet wide. The dip of the body is not indicated. It is a coarse 
mixture of kaolinized plagioclase, quartz, and perthite. 

Pegmatite bodies in the No. 6 working. — The walls of the No. 6 working consist of granite gneiss that 
has been shattered and invaded by pegmatite in the form of lenses, streaks, stringers, and irregular bodies. 
Most of the bodies are small, an inch to a few feet in thickness, and a few feet to a few tens of feet in length. 
They form a more or less interconnected complex that could be shown only on a map at natural scale. Both 
crosscutting fractures and fractures along foliation have guided emplacement. Stringers along a set of 
fractures that strike about N. 52° E. and dip about 72° NW. are locally prominent in the eastern part of the 
cut. Granite gneiss separating the bodies is conspicuously feldspathized in places. Some of the small bodies 
are essentially homogeneous, some are distinctly zoned (fig. 6). They consist of fine- to coarse-grained 
plagioclase-quartz perthite pegmatite with accessory biotite. 

Midway along the north wall there is a larger irregular body of pegmatite that extends from the floor 
of the working upward to the rim, narrowing upward. The boundaries of this body shown on the map are 
diagrammatic; beyond them there are numerous offshoots of the main body into the gneiss. By way of 
these offshoots the main body passes outward into brecciated gneiss cemented by pegmatite stringers. The 
main body contains numerous angular blocks of gneiss. Both walls and apparent inclusions of gneiss are 
markedly feldspathized, but actual contacts of pegmatite and gneiss range from sharp to fading. The peg- 
matite has a vague zonal structure. Adjacent to its walls and the apparent inclusions it consists of medium- 
to coarse-grained and plagioclase-quartz-perthite pegmatite with accessory biotite in thin books and plates 
up to 1 foot in diameter. Most of the books along the margin are oriented perpendicular to the contact. . The 
pegmatite is coarser inward, and graphic intergrowths of plagioclase and perthite are prominent. The ap- 
parent core consists of large crystals of perthite (free of quartz), coarse plagioclase, minor interstitial 
quartz, and accessory biotite in plates up to IV2 feet long, 1 foot wide, and half an inch thick. The biotite 
plates cut sharply across the feldspars. For a time this pegmatite body was the source of the feldspar pro- 
duced by the Blue Ridge Mining Co. 

The most recent operations were in the pegmatite body exposed in the west cut, a body probably con- 
nected with the one described in the preceding paragraph. The pegmatite in the west cut has uneven but 
roughly parallel walls that strike east-northeast in general and have steep but varied dips. In December 
1947 (see plan of West cut, pi. 15), the pegmatite body was 22 feet in maximum width at floor level. Coarse 
biotite schist formed the northwest wall ; the contact was marked by closely spaced shear surfaces both in 
pegmatite and in wall rock. The southeast wall was granitic gneiss, in frozen contact with the pegmatite. 
The pegmatite ended against granite gneiss in the entrance to the cut; the pegmatite thus appeared to be 
plunging southwestward. 

The pegmatite showed an asymmetrical zonal structure. A narrow border zone was succeeded inward 
by a wall zone 3 to 5 feet thick composed of medium- to coarse-grained plagioclase and quartz with subordi- 
nate perthite and accessory biotite. Inside this, on the southwest side of the pegmatite, there was a unit 
composed of coarse to very coarse blocky perthite, interstitial massive quartz, and subordinate intergrown 
quartz and plagioclase with striplike Crystals of biotite. Between this unit and the wall zone along the 
northwest wall was material similar to that of the intermediate zone of the north pegmatite. The struc- 



80 



Feldspar Deposits of the Bryson City District, North Carolina 



Plate 16. 




EXPLANATION 



Overburden and fill 



Pegmatite, undivided 



ELEV. 
21 80'-fc 



2160'- 



2 1 4 0'- 



212 0'" 



2100' 







Perthite-plagioclose- quartz pegmatite 



;;^i 



Plogioclase-quartz-perthite pegmatite 



Plagioclase-quartz pegmatite, 
with various amounts of perthite 



at point B of map 
Elevation 2123 feet *& 



, Granite gneiss 

> Strike and dip of foliation 

1 "/ / </ 

/ / / 

Exposed with dip Approximate Inferred 

Contacts of pegmatite with wall rock 



Exposed or approximate Inferred 

Contacts between pegmatite units 



Limit of exposure 
Rim of excavation 
Limits of underground workings 
Potthole: showing type of rock exposed 

Dump (dashed contours) 



20 40 60 80 100 Feet 

I I 

Scale 

Contour Interval 5 Feet 

Datum is approximately mean sea level 

Mopped by A. L. Bush, December 1946 








Granite gneiss with layers 
of biotite schist 




Plan of upper working 
at point B of map. 
Elevation 2137 feet 



South McCracken Mine 

Swain County, North Carolina 

Geologic Map, Plan, and Cross Section 



tural relationships of the two inner units were not indicated in the limited exposures available for inspec- 
tion. 

In the upper part of the open cut, the pegmatite is successively offset to the southeast and along gently 
dipping faults marked by red clay gouge. These faults may be landslip surfaces. There is abundant indi- 
cation of landsliding in the area of the cut, and slides from the slope northwest of the mine hampered opera- 
tions in the winter of 1946-1947. 



Feldspar Deposits of the Bryson City District, North Carolina 81 

Some feldspar of No. 2 grade has been recovered from this working. Further operations southwest- 
ward along the strike of the body will require the removal of large amounts of overburden. 

In the east end of the No. 6 working, a 60-foot adit with two short drifts to the northwest and west has 
been driven northeastward. It is known as the magazine tunnel. It exposes stringers and lenses of peg- 
matite in feldspathized granitic gneiss and a larger, apparently lenticular body that strikes about N. 40° E. 
and probably dips steeply west. The lenticular body is exposed for nearly 60 feet along the strike and has a 
maximum width of at least 14 feet. Near its south end it is cut by a fault that strikes N. 42° E. and dips 54° 
NW. The pegmatite is a medium- to coarse-grained mixture of kaolinized plagioclase and quartz, with 
subordinate to minor perthite and abundant accessory biotite. Inclusions of granitic gneiss range from 
those that are little affected to those that are converted to fine-grained massive aplite. In places biotite 
metacrysts up to 1 inch in diameter are strikingly developed in the gneiss adjacent to the pegmatite. 

The working is said to have been made many years ago during kaolin mining and is now nearly blocked 
in places by material caved from the roof. The pegmatite is in no respect promising as a potential source 
of commercial feldspar. 

Summary. — Of the pegmatite bodies exposed at the McCracken mines, only the north pegmatite thus 
far shows indications of a sizable body of feldspar of commercial grade. Further exploration should be 
aimed at determining whether the apparent core of the pegmatite persists at depth. 

SOUTH MCCRACKEN PROSPECT 

By Alfred L. Bush and E. N. Cameron 

The South McCracken prospect (pi. 1, no. 13) is approximately 300 feet southwest of the McCracken 
No. 6 working and about 500 feet northeast of the main working of the Cox mine. It lies at elevations of 
2,115 to 2,160 feet and is located on the southwest flank of a spur that extends southeastward from the main 
ridge bounding the lowland area. Footpaths from the McCracken mine and the Cox mine lead to the pros- 
pect. The property is part of the leasehold of the Blue Ridge Mining Co. 

The workings consist of two open cuts, each leading to an adit (pi. 16). The adit from the upper open 
cut extends northwest into the hillside for 118 feet. The adit from the lower open cut is 69 feet long and 
trends N. 22° W. The upper adit may have been driven during the early period of clay mining; it was re- 
opened in December 1946 by the Blue Ridge Mining Co. The lower tunnel was driven in January 1947. The 
property was mapped by A. L. Bush. Concurrently with the mapping, surface exploration by means of post- 
holes and a shallow trench was carried out. 

Exposures in the various workings indicate that the area is underlain by three, possibly four, pegma- 
tite bodies enclosed in granite gneiss interlayered with biotite schist. The southwestern one of the two prin- 
cipal bodies underlies an irregular area 72 by 74 feet in maximum dimensions. The contact of this body 
with granite gneiss is exposed at the northern end of the 37-foot trench west of the adits ; the contact strikes 
N. 52° E. and dips 35° NW. The foliation of the gneiss there strikes N. 51° E. and dips 72° NW. 

This pegmatite body consists of a fine-grained plagioclase-quartz-perthite border zone a fraction of an 
inch thick, a medium- to coarse-grained wall zone of plagioclase-quartz-perthite pegmatite IV2 feet thick 
(in the trench), and an inner zone (the apparent core) composed of coarse-grained to very coarse-grained 
plagioclase-quartz-perthite pegmatite. The apparent core has minor amounts of biotite and is characterized 
by graphic and irregular intergrowths of quartz and feldspar. The zonal structure is indistinct. 

The pegmatite discovered by the open cuts and appended adits is a discordant, irregular-walled body ; 
possibly it is connected with the southwestern body at depth. Information as to its structure is summariz- 
ed on plate 16. The border and wall zones resemble those of the southwestern pegmatite. The wall zone is 
discontinuous, and in the southwest upper open cut the intermediate zone lies directly against the border 
zone. Strips of biotite up to 1 inch long are present in the wall zone. The intermediate zone is similar to 
the apparent core of the southwestern body. It is characterized by crystals of plagioclase and perthite up 
to 4 feet in diameter. Some of the crystals are massive, some are entirely or partly intergrown with quartz. 
Quartz in large masses is common, and striplike biotite crystals up to 6 inches long are present. The core 



82 Feldspar Deposits of the Bryson City District, North Carolina 

of the pegmatite consists of massive perthite and massive plagioclase, in crystals 1 to 4 feet in diameter, with 
large interstitial masses of quartz. 

Two postholes, one about 12 feet east of the entrance to the lower open cut, the other about 60 feet east 
of the entrance to the upper open cut, struck pegmatite. Whether these bodies are separate or are connected 
in some way with the two principal bodies is unknown. 

The only exposed unit bearing feldspar of commercial grade is the core of the northeastern pegmatite. 
This core contains perthite of No. 1 grade. The plagioclase associated with it is entirely kaolinized, like the 
plagioclase in all the pegmatites, but there are indications that the lower limit of drastic weathering may 
not be far below the head of the lower adit. There is little likelihood of profitable mining, however, unless 
the small bodies exposed on the property are projections from a large body at depth. There is no evidence 
of downward expansion. 

Mccracken southeast prospect 

The McCracken southeast prospect (pi. 1, no. 16) is 2,400 feet N. 65° E. of Sherrill Gap, on land includ- 
ed in the leasehold of the Blue Ridge Mining Co. It lies about 200 feet southwest of Mr. McCracken's house. 
A bulldozer was used in 1946 by the Blue Ridge Mining Co., operators of the McCracken mine, to strip over- 
burden at the prospect. 

Three nearly parallel, dikelike bodies of pegmatite are exposed at the prospect. The west and middle 
pegmatites are 9 feet apart. They strike N. 37° E. and dip 70° NW. The east pegmatite and middle peg- 
matites are 18 feet apart where exposed. The east pegmatite strikes N. 29° E. and dips 83° W. The peg- 
matites range from 1 to 21/2 feet in thickness and appear to be at least 150 feet in strike length. They are 
coarse mixtures of blocky perthite, blocky plagioclase, and quartz. 

COX NO. 1 MINE 

General information. — The Cox No. 1 mine (pi. 1, no. 14) lies about 1,900 feet N. 52° E. of Sherrill Gap, 
straddling the ravine occupied by one of the headwater tributaries of Bryson Branch. The mine is on land 
reported to be owned by S. D. McKinney, Little Switzerland, N. C. It was operated from 1940-1948 by the 
Blue Ridge Mining Co., Spruce Pine, N. C. The mine is reached by a short graveled access road that turns 
northward from the Sherrill Gap road near the sharp bend at the 2,040-foot contour. 

The mine probably was opened about 1910; at this time the upper parts of the Cox No. 1 pegmatite were 
worked for kaolin. A series of open cuts, now badly slumped, was made south of the hoist house (pi. 17) 
over an area 140 feet long and about 120 feet wide. Other workings — open cuts, and possibly shafts — were 
made on the site of the present main working. No records of kaolin production are available. In the early 
1940's, the Blue Ridge Mining Co. discovered a sizable body of commercial feldspar. The company's opera- 
tions continued with little interruption from 1940 to 1948. From 1948 to June 1949, further mining was 
done by M. H. Cox. 

The Blue Ridge Mining Co. produced about 30,000 tons of feldspar, mostly of No. 2 grade. Costs per 
ton are reported as $5.90 in 1940, but by 1948 costs had risen to $8.85 per ton. Increased labor and freight 
charges were largely responsible. 

The main working is a roughly oval open cut 128 feet in length and 100 feet in maximum width (pi. 3, 
B) ; its floor is at 2,065 feet and its rim ranges in elevation from 2,143 feet to 2,203 feet. In the fall of 
1946 a chamber with floor at elevation 2,110 feet and roof at 2,020 feet was developed in the northwest wall 
of the open cut. Two shallow pits and a slumped open cut 23 feet long, 15 feet wide, and 6 feet in maximum 
depth, also were made on the slope north of the main working. 

Form and structural relations of the pegmatite. — The pegmatite is an irregular elongate lens striking 
nearly north and dipping irregularly but steeply west. The lens is about 450 feet long and at least 100 feet 
in maximum thickness. Contacts of the body are partly exposed in the workings ; outside the workings a 
number of postholes and shallow trenches put down in the course of the present study have established 
the general outlines of the body. The pegmatite cuts obliquely across the belt of border gneiss ; its northern 
tip is enclosed in metasedimentary rocks, whereas the southern end is in granite gneiss. The northern end 



Feldspar Deposits of the Bryson City District, North Carolina 83 

of the pegmatite is a double wedge, with apices separated by a sharp reentrant of metasedimentary rocks. 
The pegmatite widens southward irregularly, and beneath the derrick site at the main working it apparent- 
ly bulges abruptly southeastward across the f ootwall. South of this point the f ootwall is concealed by dumps 
for nearly 300 feet, and its form and precise position are uncertain. The hanging wall south of the pit is 
irregular; a prominent southeastward jut causes a marked constriction of the pegmatite in the vicinity of 
the hoist house. The relation of the form of the pegmatite to the structure of the wall rocks is not fully 
indicated, but the unevenness of the walls appears to be due, in part at least, to control by fractures, prob- 
ably fractures subsidiary to the main fracture along which the pegmatite must have been emplaced. 

The plunge of the pegmatite body is uncertain. The narrowing of the pegmatite northward, where the 
topographic surface is relatively high, might be taken to suggest that the body is plunging in that direction. 
The internal structure, however, suggests strongly that the plunge of the body is westward, and probably 
closer to the direction of dip of the pegmatite than to the direction of strike. 

The foliation of the wall rocks in the vicinity of the pegmatite strikes N. 22°-78° E., averaging about 
N. 40° E. ; dips range from 49° NW. to vertical. Bedding and foliation of the metasedimentary rocks are 
parallel so far as can be determined. Contacts with pegmatite are sharp at most places. On the west rim of 
the main working, border gneiss shows a biotite-rich selvage half an inch to 2 inches wide, and the folia- 
tion of the border gneiss is dragged northward for a few feet along the contact. Small apophyses of the 
main pegmatite extend into the walls at places. Along the contacts shown on the plans of the 2,110- and 
2,120-foot levels (pi. 17) , stringers, lenses, and layers of pegmatite Vi inch to 5 inches thick and as much as 
12 feet long are injected into feldspathic quartzite, chiefly along the bedding. Patches of aplitic material 
also are present in the quartzite. 

The pegmatite is intersected in the main working by a number of shear surfaces coated by greenish seri- 
cite. The most prominent group at the time of mapping was a series of closely spaced surfaces that defined 
most of the wall between the floor of the open cut and the floor of the chamber. This shear zone strikes N. 
88° E., dips 65°-72° S., and shows striations plunging 42°, S. 62° E. Numerous other shorter shear surfaces, 
of several sets ranging in strike from N. 65° W. to N. 70° E. and in dip from 50° to 80° S. to SW., are exposed. 
Displacements along the surfaces are negligible. 

Composition and internal structure of the pegmatite. — The pegmatite consists essentially of plagioclase, 
perthite, and quartz, with minor amounts of biotite, accessory magnetite and garnet, and traces of pyrite 
and fiuorite. Six zones, most of which are distinguished by textural contrasts, are recognizable within the 
pegmatite. The outermost zone is a fine-grained border zone Vi inch to 6 inches in thickness. It is com- 
posed of plagioclase, quartz, subordinate to minor amounts of perthite, and accessory magnetite, biotite, and 
garnet. In places the zone is rich in magnetite crystals ranging up to % inch in diameter. Wisps of felds- 
pathized border gneiss derived from slabby xenoliths are exposed in two places along the hanging wall. 
Numerous flakes of biotite as much as Via by */4 by 1/16 inch are oriented subperpendicular to the contacts. 

Inside the border zone is a wall zone 2 to 4 feet thick essentially similar in composition to the border zone 
but coarser in texture and higher in average content of massive plagioclase. The zone lacks perthite in 
places, particularly along the contacts in the south working, and it varies in distinctness depending on the 
proportion of perthite. The zone is lacking along the hanging wall in the west end of the open chamber in 
the main working, and inner zones are directly in contact with the border zone. The wall zone grades in- 
ward into the outer intermediate zone by increase in grain size and by decrease in the proportion of mas- 
sive plagioclase. 

Inside the wall zone is an outer intermediate zone composed of very coarse-grained plagioclase-quartz- 
perthite pegmatite with minor amounts of biotite and accessory magnetite and garnet. Perthite forms scat- 
tered anhedral to subhedral crystals up to six feet in maximum dimension, in part massive and in part in 
irregular or graphic intergrowth with quartz. Much of the plagioclase forms irregular intergrowths with 
quartz, but some forms graphic intergrowths and some occurs as massive crystals up to 6 inches in diam- 
eter. Biotite forms unevenly distributed strips up to 6 inches long, IV2 inches broad, and Vs mcn thick 
and also forms slablike books along fractures cutting all the other minerals. Magnetite is locally abundant 
in crystals ranging from Vs to 1 mcn m diameter and averaging % inch. The zone shows much variation 
in mineral proportions from place to place. On the average, plagioclase and quartz are about equal in 



84 Feldspar Deposits of the Bryson City District, North Carolina 

amount and predominate over perthite. Fine-grained pyrite is found in places along fractures and is evi- 
dently a late mineral. Some biotite strips are partly altered to chlorite. 

The outer intermediate zone grades into the middle intermediate zone by gradual change in texture and 
mineral proportions. The predominant components of this zone are graphic intergrowths of quartz with 
perthite and plagioclase. The feldspar crystals range from 2 to 6 feet in diameter. Massive perthite and 
3-inch to 1-foot crystals of massive plagioclase also are present, and massive quartz forms small areas inter- 
stitial to the feldspars. Strips of biotite and clusters of strips up to a foot long, 4 inches broad, and 2 inches 
thick are present. Magnetite and garnet are minor accessories. The proportion of plagioclase to perthite 
in this zone varies considerably. Perthite seems to predominate over plagioclase along the hanging-wall 
side of the pegmatite, but plagioclase is the more abundant mineral along the footwall side. The shape of 
this unit is not fully known, because most of it is mined out, but the number of exposures of the unit in the 
walls are limited. It appears to form an irregular, incomplete envelope, 10 feet to perhaps 34 feet in thick- 
ness, around the innermost zones. It is exposed chiefly in the northern half of the open cut, but a small body 
of similar material in the southern wall of the open cut near the base may represent the southward exten- 
sion of the zone. A second segment of the zone appears to be represented in the old clay workings south of 
the blacksmith house, but the material is too poorly exposed to be identified with certainty. 

In the main working the two inner zones of the pegmatite, the perthite-quartz zone and the quartz core, 
are exposed chiefly at the north end. Here a segment of the core forms a roughly pipelike body, 3 feet to as 
much as 9 feet in diameter, that appears to plunge about 50°, S. 70°-75° W. At the time of mapping this 
body was exposed in the roof of the chamber and in the wall of the main working below the chamber floor. 
Its margins are most irregular; crystals of perthite project into it from the adjacent perthite-quartz zone. 
The core consists almost entirely of quartz but locally contains scattered crystals of perthite. Both perthite 
and quartz along the margins of the core are crisscrossed in places by numerous fracture-controlled plates of 
biotite that are fractions of an inch thick and up to 1 foot broad. One uneven biotite-coated shear surface 
is exposed over an area 4 by 4 feet. 

The perthite-quartz zone forms an irregular envelope 4 feet to about 25 feet thick around the quartz 
core and appears to plunge approximately parallel to the quartz core. The zone consists essentially of mas- 
sive perthite, in crystals up to 5 by 4 feet, and quartz, which occurs chiefly as interstitial masses a few 
inches to 8 inches in diameter. Plagioclase is subordinate but forms stout white to greenish crystals 2 
inches to 1 foot in diameter. The outer portion of this unit contains some quartz in graphic intergrowth 
with perthite. At most places the zone is separated from the walls of the pegmatite by the middle and outer 
intermediate zones, but in the northwest corner of the chamber these zones are absent, and the perthite- 
quartz zone is separated from the wall rock only by a border zone too thin to be shown on the map. 

The perthite-quartz zone and quartz core exposed in the chamber were discovered only during the most 
recent stages of operations. The operators state that the main working followed a small quartz core partly 
or perhaps entirely enclosed in a much larger segment of the perthite-quartz zone. The two units together 
formed a pipelike body that was mined downward from the northeastern end of the open cut to the floor. 
The pipe plunged steeply in a direction probably between southwest and west. The approximate eastern 
boundary of the perthite-quartz zone and its western contact with the quartz core were uncovered on the 
floor of the main working beneath debris and are shown in the plan of the 2,068-foot level. It seems proba- 
ble that the pipelike body was actually the thickened portion of an elongate lens, and that in the upper part 
of the working the lens extended southward along the strike as far as the south wall of the open cut. The 
perthite-quartz pegmatite shown on the south rim of the open cut (pi. 17) may thus represent the extension 
of the body containing the main shoot. 

The relationship between the main shoot and the segment of the perthite-quartz zone exposed in and 
near the chamber cannot be determined at present. It is entirely possible that the segment was connected 
with the main shoot, but it is also possible that either the middle intermediate zone or the outer intermed- 
iate zone, or both, extended around the segment now exposed at the north end and separated it from the 
core. Precisely this relationship seems to hold true in the upper part of the north wall, where the northern 
edge of the main shoot is separated from the perthite-quartz pegmatite and quartz core segment of the cham- 
ber. 

In the open cut on the slope north of the mine, perthite-quartz pegmatite enclosing a small lens of quartz 
is exposed. The relationship of this material to the perthite-quartz body exposed in the chamber in the main 



Feldspar Deposits of the Bryson City District, North Carolina 85 

working has an important bearing on the tonnage of commercial feldspar still remaining in the mine. The 
core segment and associated perthite-quartz zone in the chamber, projected upplunge, would intersect the 
surface in the vicinity of the small open cut, but exposures are as yet so limited that it is hardly safe to con- 
clude that they are the downward extension of the body exposed in the cut. 

Kaolin. — Much of the plagioclase present in the upper part of the pegmatite is altered to kaolin, some 
of which is pure white, some of which is stained by iron oxides. The bottom of the weathered zone around 
the main working lay not far below the original surface, but in the clay working south of the blacksmith 
house weathering extended to somewhat lower elevations, and part of the kaolinized upper portion of the 
pegmatite is preserved. In part the clay workings there seem to have followed a plagioclase-rich portion 
of the wall zone along the footwall of the pegmatite, but much back-fill is present in the cut, and the walls 
have slumped so badly that it is difficult to determine the extent and objectives of the clay workings. A 
ridge of material was left extending north-south, roughly through the middle of the pegmatite. Scattered 
exposures suggest that the ridge was not mined, because it contains a comparatively high proportion of 
unkaolinized potash feldspar. 

Feldspar. — Feldspar produced from the mine has come largely from the pipelike body mined downward 
in the central portion of the main working, but production during the winter of 1946-47 came from the 
chamber. The pipelike body is said to have yielded considerable amounts of No. 1 feldspar as well as a 
good grade of No. 2 feldspar, but mining has extended outward considerably beyond the boundaries of the 
shoot into the outer intermediate zone. This zone and the middle intermediate zone were undoubtedly the 
source of much of the large proportion of No. 2 feldspar reportedly produced from the mine. The feldspar 
produced is reddish, light buff, or greenish perthite, and white to greenish plagioclase. Crystals sufficiently 
free of intergrown quartz can be separated and marketed as No. 1 feldspar. The bulk of the material re- 
covered, both plagioclase and perthite, contains quartz in graphic or irregular intergrowth and is of No. 2 
grade. Biotite, magnetite, and garnet, objectionable impurities of all zones, must be eliminated by hand 
sorting. Exploration has so far disclosed no shoot that appears to be comparable in size to the one mined 
down to the present floor level of the main working. This shoot has not yet been bottomed but is reported 
to be somewhat narrower than in the upper levels. Neither the extent of the smaller shoot exposed in the 
chamber nor its relationships to the main shoot are indicated, and no estimate of reserves of No. 1 and 
No. 2 feldspar can be made until further development work is done. The segment of the perthite-quartz zone 
exposed on the slope above the quarry offers some promise as a potential source of feldspar, and its precise 
extent and thickness and its relationship to the shoot exposed in the chamber should be determined. The 
perthite-rich material indicated by scattered exposures and postholes in the south working merits inexpen- 
sive exploration by means of pits and trenches. It seems unlikely, however, that a deposit of feldspar of 
commercial size is present in this part of the pegmatite unless the pegmatite expands appreciably down dip. 
The dips of the contact around the southern end of the pegmatite lend some support to this possibility. The 
dip of the footwall at the two places where it has been exposed by test pits ranges from 57° to 87° NW., 
whereas the dip of the hanging wall at three places exposed ranges from 35° to 62° NW. The walls of the 
pegmatite are known to show pronounced changes in strike and dip within very short distances, however, 
and too much reliance cannot be placed on the limited data available. 

COX NO. 2 DEPOSIT 

By Alfred L. Bush and E. N. Cameron 

The Cox No. 2 deposit (pi. 1, No. 15) lies approximately 180 feet west-southwest of the Cox mine main 
working. The deposits straddles the crest of a southeasterly trending ridge and extends to the bottom of 
the ravine on the southwest side of the ridge. Two foot trails connect the deposit with the Cox mine. The 
pegmatite probably was discovered during the early 1900's. Either then or later it was worked for clay. 
The mine is on land owned by a Mr. Cox and is included in the leasehold of the Blue Ridge Mining Co. of 
Spruce Pine, N. C. No feldspar mining has been attempted. 

The principal working is an open cut 90 feet long, 80 feet wide, and 50 feet deep (pi. 17). The floor 
is concealed beneath fill and slumped material of unknown depth. Several shallow pits on the slope south 
of the mine were evidently made during the early operations. A series of postholes and shallow trenches 



86 Feldspar Deposits of the Bryson City District, North Carolina 

was excavated in the course of the present investigation with the purpose of determining the extent and 
structure of the pegmatite body exposed in the mine. 

The pegmatite appears to be a stout, blunt, irregular lens. It trends N. 42° E., dips steeply northwest, 
and transects the contact of border gneiss with metasedimentary rocks. It is associated with a marked 
flexure of the wall rocks that is registered in the pattern of the contact of the metasedimentary rocks with 
border gneiss. Because of this flexure the strike of the foliation of the country rocks swings from N. 32° 
E. west of the mine, to N. 67° E. in the open cut, and back to about N. 44° E. along the west rim of the main 
working of the Cox No. 1 mine. Dips range from 64° to 85° NW. 

The pegmatite is exposed over a length of 170 feet and is 38 to 85 feet in outcrop width. Dips of its 
walls range from 48° NW. to vertical; the variation is marked and irregular within short distances, hence 
it is unecrtain whether the pegmatite is broadening or narrowing at depth. A roll of the contact at the 
northern corner of the open cut plunges 26°, N. 88° W., but there is no other suggestion of the plunge of the 
pegmatite. Contacts of pegmatite with wall rocks are sharp, save locally where the quartzite has been f elds- 
pathized as much as 2 inches from the contact. The wall rocks and the pegmatite (except for perthite and 
quartz) are thoroughly decomposed, and structural and lithologic details are not satisfactorily shown. 

The pegmatite appears to consists of four zones : a border zone, a wall zone, an intermediate zone, and 
a core. The border zone consists of fine-grained quartz, plagioclase, and perthite, and is generally Vs to V4 
inch thick. The wall zone, 4 inches to perhaps 7 feet in thickness, consists of irregularly intergrown med- 
ium- to coarse-grained kaolinized plagioclase and quartz, with minor amounts of perthite and unevenly dis- 
seminated sericite and green muscovite. The boundary between the wall zone and the intermediate zone is 
marked by increase in grain size and by the appearance of graphic intergrowths of quartz and feldspar. 
The intermediate zone, 7 to at least 20 feet thick, is characterized by coarse to very coarse crystals of kaolin- 
ized plagioclase and perthite and by scattered books of biotite up to 4 by 4 by 2 inches. Perthite and plagio- 
clase are in part graphically or irregularly intergrown with quartz. The perthite-quartz zone, the apparent 
core of the pegmatite, consists of massive potash feldspar in crystals IV2 to 4 feet in diameter. Parts of 
the crystals show irregular or graphic intergrowth with quartz. Scattered irregular quartz masses, 
against which the perthite is commonly euhedral, are present. 

The perthite-quartz zone is the only apparent potential source of commercial feldspar in the pegmatite. 
Its greatest known thickness, in the trench along the line of Section D-D' on plate 17, is only 15 feet, and 
exposures in a trench excavated to explore the southwest rim of the open cut suggest that the core splits 
into two prongs between the two trenches. The lack of any indication of a perthite-quartz zone in the 
area southwest of the open cut is puzzling unless the pegmatite plunges southwest. If so, unroofing of the 
crest of the pegmatite by erosion has not progressed far enough to uncover the core. An adit driven about 
N. 10° E. from the midpoint of trench H should serve to determine this, but unless the pegmatite broadens 
greatly downward, discovery of a sizable body of commercial feldspar is unlikely. 

PEGMATITE ON ROAD TO COX MINE 

On the access road leading from the Sherrill Gap road to the Cox Mine, 1,650 feet N. 73° E. of the gap, 
a small pit has been made by the Blue Ridge Mining Co. in a tabular pegmatite body that strikes N. 80° E. 
and dips 75° S. (pi. 1, no. 18). The pegmatite cuts granite gneiss that strikes N. 53° E. and dips 64° NW. 
and appears to be exposed also a short distance along the strike in the cut bank of the road. The pegmatite 
is 6 or 7 feet thick and consists of a quartz core that is about 3 feet wide and is flanked by feldspathic zones. 

A small tonnage of high-grade potash feldspar is reported to have been taken from the pit, but the peg- 
matite body appears much too small to support a profitable mining operation. 

LACKEY MINE 

A pegmatite exposed in a cut on the Sherrill Gap road, 1,300 feet N. 62° E. of the gap (pi. 1, no. 17) , 
was prospected early in 1947, reportedly by two brothers named Lackey, of Bryson City. Some feldspar of 
No. 2 grade is said to have been produced and trucked to the mill of Interstate Feldspar Corp. at Dillsboro. 
In April 1947, an irregular inclined chamber about 20 feet deep had been opened downward to the north- 
east from the northwest edge of the road. Twenty feet southeast of the road there was an open cut 15 



Feldspar Deposits of the Bryson City District, North Carolina 87 

feet long leading to an adit about 18 feet long. The adit was driven by the sons of Mr. Walter Hyatt, owner 
of the land on the south side of the road. 

The incline is just below the rounded crest of a pegmatite body; the crest appears to plunge about 53°, 
N. 80° W. The exposed width of the body at road level is about 30 feet. The incline is in very coarse- 
grained perthite and plagioclase, most of which is in graphic intergrowth with quartz. Individual crystals 
range up to 6 feet in length. The feldspars are cut in places by slablike crystals of biotite up to 18 inches 
broad. The plagioclase is partly kaolinized at the surface but is considerably harder in the bottom of the 
working. The adit on the Hyatt property is in similar pegmatite. 

Systematic prospecting is needed to determine the shape, size, and internal structure of the pegmatite. 

HYATT PROSPECT NO. 1 

The Hyatt prospect No. 1 (pi. 1, no. 19) is on land owned by Mr. Walter Hyatt of Bryson City. It lies 
600 feet S. 84° E. of Sherrill Gap. In December 1946 and January 1947 Mr. Hyatt excavated an open cut 
27 feet in length. The cut trends N. 20° W. and follows an irregularly tabular pegmatite body cutting gran- 
itic gneiss. The pegmatite is at least 40 feet long and is 2 to 7 feet thick, but it may be thicker beyond the 
limits of the working. The foliation of the gneiss in the working strikes N. 51° E. and dips 89° SE. 

The part of the pegmatite exposed early in 1947 is a medium- to coarse-grained mixture of plagioclase 
with subordinate perthite irregularly intergrown with quartz. Six feet below the original ground surface 
the plagioclase is hard and little kaolinized. 

HYATT PROSPECT NO. 2 

The Hyatt prospect No. 2 (pi. 1, no. 20) is located on the farm of Mr. Walter Hyatt of Bryson City, on 
the opposite side of the farm access road from the Hyatt Barn. The prospect is 1,260 feet N. 86° E. of Sher- 
rill Gap. Excavation in the bank of the road early in 1947 exposed a tabular pegmatite body 9 feet thick 
cutting granitic gneiss. The pegmatite strikes about N. 70° W. Its hanging wall has an average dip of 
70° SW. ; its footwall dips 61° SW. It shows a border zone, a wall zone, and a core. The border zone is less 
than an inch thick and consists of fine-grained plagioclase-quartz-perthite pegmatite. The wall zone is 2V2 
to 3!/2 feet thick and consists of medium- to coarse-grained plagioclase-quartz pegmatite with subordinate 
perthite and accessory biotite. The core is composed of blocky perthite and massive interstitial quartz, with 
accessory biotite in slablike crystals. Test pits show that the pegmatite extends at least 125 feet northwest 
along the strike from the road, and that the core is present throughout this distance. 

BRANTON MINE 

Description. — The Branton mine (pi. 1, no. 21) lies 3,100 feet N. 22° W. of Franklin Grove Church, 
near the base of a spur that extends eastward from the ridge west of the Bryson City lowland. The mine 
is reached by way of the graveled road leading northward from Franklin Grove Church to a sharp bend 
2,250 feet N. 34° W. of the church. From this point a dry-weather road leads to the mine. 

The mine is on land owned by Mr. James M. Branton. It was prospected in 1942. Feldspar Milling 
Corp. worked the property intermittently under lease from September 1943 until April 1944. Approximate- 
ly 120 tons of No. 1 potash and soda feldspar are said to have been recovered. An open cut approximately 40 
feet square and 10 to 50 feet deep was excavated in the side of the spur (pi. 18) ; and the northwestern of 
the two shafts shown on the map, now partly filled, was excavated in the floor to a depth reported to be 
nearly 28 feet. The property was leased to the Whitehall Co. in 1946. The open cut was enlarged in August 
and early September, and a large excavation was made by bulldozing. An entrance cut 19 feet wide, with a 
floor at an average elevation of 2,016 feet, was made, and a shaft 30 by 19 feet was sunk at the head to ele- 
vation 1,986 feet. About 40 tons of feldspar was recovered, but the yield of feldspar per ton of rock moved 
was so low that operations were discontinued. In April 1947, the owner began further development work 
at the head of the open cut. 

The pegmatite body worked is an irregular lens about 120 feet long and 35 feet in maximum thickness. 
Its average strike is approximately N. 37° W. and its average dip is probably about 65° SW. About 20 or 



88 



Feldspar Deposits of the Bryson City District, North Carolina 






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Feldspar Deposits of the Bryson City District, North Carolina 89 

25 feet from its southeast end it is offset about 18 feet to the northeast along a narrow fault zone, the prin- 
cipal fractures of which strike N. 24°-31° E. and dip 65° to 71° NW. Striations on one of the surfaces plunge 
N. 85° W. at an angle of 58°, suggesting an oblique slip that would require an upward movement of the 
hanging wall. 

The pegmatite lies athwart the belt of border gneiss. The gneiss is narrow and much interlayered with 
granite gneiss, and it contains thin layers that may represent metaperidotite. Like the Cox No. 2 pegma- 
tite, it may occupy a fracture associated with a local flexure of the wall rocks, but the precise structure is 
doubtful owing to the lack of exposures outside the workings. Postholes and a shallow trench put down in 
the course of the present investigation indicate that the northwest tip of the lens lies just within the meta- 
sedimentary rocks. The tip was exposed, though poorly, in the trench, where it plunges N. 40° W. at an angle 
of about 47°. The value of this reading as an indication of the over-all plunge of the pegmatite is ques- 
tionable. The foliation of the wall rocks in the vicinity of the workings strikes N. 36° to 54° E. and dips 
52° to 86° NW. Contacts of wall rock with pegmatite are sharp except where obscured by thorough decom- 
position. 

The pegmatite is distinctly but irregularly zoned. Along the walls there is a fine-grained border zone 
composed of plagioclase-quartz-perthite pegmatite with scattered small biotite flakes. Plagioclase in part is 
in graphic intergrowth with quartz. Inside this zone is a coarse to very coarse wall zone. It is composed 
of white crystals of plagioclase ranging from 2 by 8 inches up to 2 by 2 feet, in graphic or irregular inter- 
growth with quartz, scattered cream to reddish-brown perthite crystals of similar dimensions, in part in 
graphic intergrowth with quartz, and scattered crystals of massive plagioclase. Plagioclase is entirely 
kaolinized in most of the working. Partly limonitized biotite, in strips up to a foot long, 2 inches broad, and 
V2 inch thick, occurs scattered through the plagioclase-quartz graphic intergrowths. Flakes, books, and nests 
of books of muscovite less than an inch in diameter occur sparsely through the zone. Fine-grained musco- 
vite is found in places and appears to be associated with albite formed at the expense of perthite and subse- 
quently kaolinized. At the southeast end of the southeast shaft this material appears to form the full width 
of the pegmatite, but at the opposite end it is separarated from the quartz-perthite core of the pegmatite 
by an outer intermediate zone that is 5 feet thick along the hanging wall and 3 to 8 feet thick along the foot- 
wall. This zone is similar to the wall zone, except that it is rich in irregular streaks and patches that range 
up to 8 by 4 inches and are composed of quartz intergrown with anhedral muscovite books Vi to 1 inch broad. 
The books are commonly elongated parallel to the c axis and range in length up to 4 inches. Biotite is vir- 
tually lacking in most of this zone, but the zone grades outward into the wall zone. Where the outer inter- 
mediate zone is directly in contact with the core, the contact is marked by scattered books of gray-green 
muscovite of scrap quality. The books range from 2 inches in breadth and an inch in thickness up to 1 foot 
in length, 6 inches in breadth and 4 inches in thickness. 

The core of the pegmatite is best exposed in the northwest shaft and in the partition separating the 
two shafts. It is an irregular- walled body that is 1 foot to 8 feet thick and dips about 61° SW. It consists 
of massive milky quartz containing scattered crystals of perthite up to 4 feet in length. Crystals of massive 
plagioclase and perthite up to 3 feet in length are scattered along the margins with the muscovite crystals 
described above. 

The outer intermediate zone appears to wedge out northward along strike and also up dip in the north- 
west wall of the northwest shaft. In the lower part of the headwall of the open cut its position and that 
of the core are taken by a unit composed of massive perthite and massive plagioclase, with subordinate 
quartz and muscovite and accessory beryl. The composition of the zone is roughly estimated to be : 35 per- 
cent perthite, 35 percent plagioclase, 25 percent quartz and 5 percent muscovite, the last figure including a 
small fraction of a percent of beryl. The feldspars form stout crystals as much as 2 by 3 feet in cross sec- 
tion. Quartz occurs largely as masses interstitial to the feldspars but in part intergrown with the edges of 
the crystals. Muscovite forms numerous books ranging from V2 to 10 inches in diameter and 1/2 inch to 
IIV2 inches thick. The muscovite is gray-green, ruled in 2 to 3 directions, wavy, partly tanglesheet, and cross- 
fractured. No sheet-bearing mica was observed. The larger books lie at the centers of irregular bodies of 
quartz intergrown with small anhedral muscovite books. A few muscovite books contain biotite in parallel 
intergrowth. The quartz-muscovite bodies range up to 5 inches by 1 foot in cross section ; yellowish-green, 
partly kaolinized beryl occurs in sparsely scattered crystals and columnar groups of parallel crystals. The 



90 Feldspar Deposits of the Bryson City District, North Carolina 

largest groups are more than 7 by 5 by 4 inches in size. The crystals appear to be more closely associated 
with quartz and plagioclase than with perthite. 

The relationship of this zone to the core of the pegmatite could not be fully determined. It resembles 
the material present in the shafts along the margins of the core, and the core appears to plunge northwest- 
ward beneath it. It seems probable that it is a hood-shaped inner intermediate zone over one end of the 
core, of a type found in pegmatites in many districts. 

Feldspar. — Feldspar produced from the pegmatite has probably been taken both from the wall zone 
and from the perthite-plagioclase-quartz unit. Mr. Branton reports that during operations conducted under 
his direction for the Blue Ridge Mining Co. the latter unit was followed downward to the southwest from 
the upper part of the open cut and lay about midway between the walls of the pegmatite. The Whitehall 
Co. shaft was sunk to explore the margins of the quartz core, but no distinct marginal zone of massive feld- 
spar was found. 

The only unit of the pegmatite that appears to contain high-grade feldspar in appreciable amounts is 
the perthite-plagioclase-quartz unit. This unit extends as much as 20 feet above the base of the headwall and 
is exposed for about 25 feet along the base ; it is not large in horizontal section. There is a good possibil- 
ity, however that this zone plunges in a southwesterly direction, passing downward beneath the west wall 
of the open cut. This possibility could be tested by cleaning out the northwest shaft and running a drift 
west-northwest from its bottom, but the operation might prove difficult. Plagioclase in the perthite-plagio- 
clase-quartz unit in the lower part of the headwall is not seriously kaolinized, but the rock has been weak- 
ened by weathering, the rocks above are thoroughly decomposed, and there has been much slumping of the 
walls of the cut. An additional hazard is a strong flow of water reportedly encountered in the shafts. 

COCHRAN PROSPECT 

The Cochran prospect (pi. 1, no. 22) lies 200 feet southwest of the Branton mine, on the crest and south- 
west flank of a low ridge. The prospect is on land reported to be owned by Mr. Carl Cochran of Bryson 
City. The property was prospected by Mr. Oscar Pittman in the early 1940's. No records of production 
are available, but the yield of feldspar was probably no more than a few tons. 

The principal working is an open cut 21 feet long leading to an adit 44 feet long. The adit runs N. 14° 
E. into the flank of the ridge (pi. 18). At 27 feet from the portal of the adit a drift extends 7 feet south- 
east, and at 34 feet a second drift with 3 appended small shallow chambers extends on a curving course to a 
point 46 feet N. 55° W. from the adit. Four small open cuts, one with a shallow underhand stope and an- 
other with a 4-foot adit, comprise the remainder of the workings. 

The pegmatite is exposed only in the main working and in the open cut north-northeast of it. It is an 
uneven-walled, tabular, discordant body that strikes approximately N. 51° W., appears to dip roughly 68° 
W., and is about 18 feet thick in the vicinity of the main workings. It is enclosed in border gneiss, the folia- 
tion of which strikes N. 48°-59° E. and dips 65° to 72° NW. Contacts of pegmatite and border gneiss are 
knife-sharp ; in detail they show angular irregularities apparently controlled by fractures. 

The pegmatite exposed in the main working consists of a border zone, a wall zone, an intermediate 
zone, and a discontinuous core consisting of 3 podlike segments enclosed in the intermediate zone. The bor- 
der zone is V4 to 1 inch thick and composed of Vs- to !/2- mc h grains of plagioclase, quartz, and perthite. 
Black spots probably represent sparsely scattered small biotite flakes. The wall zone is not well defined ; it 
is 1 foot to 2 feet thick, medium- to coarse-grained, and composed of plagioclase-quartz-perthite pegmatite 
with scattered strips of biotite. Perthite occurs as highly irregular crystals intergrown with quartz along 
their edges and their inner ends. Plagioclase is kaolinized. The intermediate zone is a medium- to coarse- 
grained mixture of plagioclase, quartz, and perthite, with minor muscovite and accessory biotite and garnet. 
Plagioclase and perthite occur in stout, subhedral to anhedral crystals as much as 6 feet in length, in part 
massive, in part in irregular or graphic intergrowth with quartz. Muscovite occurs with quartz in inter- 
growths as much as 4 by 18 inches in cross section. Haphazardly oriented and tapered strips of biotite as 
much as 18 inches long, several inches broad, and 11/2 inches thick, are sparsely scattered through the zone. 
Some of the strips are unevenly edged with intergrown quartz and muscovite. These complex masses range 
up to 2 by 6 feet in cross section. Black lumps of manganese oxides V 8 to i/ 2 inch across appear to represent 
weathered garnet crystals. 



Feldspar Deposits of the Bryson City District, North Carolina 



91 



The pods, or core segments, are 1 foot to 3 feet thick and range from 7 to 20 feet in exposed length. 
They consist essentially of coarse to very coarse massive perthite and kaolinized plagioclase with intersti- 
tial massive quartz. The margins of the pods are marked by muscovite intergrown with quartz or plagio- 
clase. The largest pod, in the northwest drift, is exposed for 20 feet along the roof and walls. It appears 
to dip about 47° SW. and has a moderate westerly plunge. A similar pod is exposed in the open cut and 
appended underhand stope north-northeast of the main working. 

Feldspar. — Some feldspar of No. 1 grade is present in the pegmatite, but most of the feldspars are so 
heavily intergrown with quartz that recovery even of No. 2 feldspar by handsorting would be costly. In 
addition, the plagioclase is all kaolinized to the depths thus far reached. Feldspar in economic concentration 
is present only in the core segments, and none of them is large enough to warrant mining. 

MASON PROSPECT 

The Mason prospect (pi. 1, no. 23) lies 2,700 feet N. 55° W. of Franklin Grove Church, on land owned 
by Mr. Zollie Mason. The workings (fig. 13) consist of 3 open cuts leading to 3 adits driven into the steep 




EXPLANATION 



S±A 



Perthite-plagioclase pegmatite 



ivy a\ 



Granitic gneiss with layers 
of border gneiss 

4 V 

Strike and dip of foliation 
80 __ — 

Contacts between pegmatite 
and wall rock, with dip 

Fault, with dip 

Rim of open cut 
Limit of underground working 



Dump (dashed contour lines) 

9 20 40 60 Feet 

SCALE ' 

Contour interval =5 feet 

Datum is approximate mean 
seo level 




Geologic plan of 
lower working 



Figure 13. Sketch Map of Workings at the Mason Prospect and Geologic Plan of Lower Workings. 



92 Feldspar Deposits of the Bryson City District, North Carolina 

slope of the ridge south of the owner's house. The lower of the two adits was driven by Mr. W. J. Alexan- 
der in 1941 or 1942. An open cut 26 feet long leads to the adit, which is 86 feet long. Both open cut and adit 
trend about N. 55° W. Twenty-six feet from the portal a drift 22 feet long extends southward from the 
adit, and another extends 10 feet northward. The upper two adits were made by Mr. Mason. Neither was 
accessible at the time the prospect was examined. 

In the middle open cut, which is 20 feet long, 5 to 6 feet wide, and 6 feet in maximum depth, a tabular 
pegmatite body 7 feet thick is exposed. The hanging wall of the body strikes N. 14° W. and dips 66° SW. 
Adjacent to this is a half -inch border zone of plagioclase-quartz pegmatite with accessory biotite. This zone 
grades inward into a 1-foot wall zone of medium-grained plagioclase-quartz-pegmatite, which passes in turn 
into a 2i/2-foot intermediate zone of coarse plagioclase-quartz-perthite pegmatite. The core of the pegmatite 
consists of coarse perthite-quartz pegmatite with accessory biotite in slablike crystals. The remainder of 
the pegmatite to the footwall is so thoroughly decomposed that its internal structure cannot be determined. 
The wall rock is interlayered granitic gneiss and border gneiss. 

The uppermost open cut, now badly slumped, appears as a trench 15 feet long, 7 feet wide, and 7 feet 
deep. The west contact of pegmatite with wall rock is exposed; it strikes N. 22° W. and has an average dip 
of 47° SW. Pegmatite is exposed for 5 feet below this contact, but the footwall contact is concealed. The 
pegmatite resembles that in the middle cut. The wall in the upper open cut consists of interlayed micaceous 
quartzite and quartz-mica schist. 

The portal of the adit in the lower working is in interlayered granitic gneiss and border gneiss, and 
these rocks enclose the pegmatites shown in the plan. The geology has been sketched on the plan with a 
minimum of control. Both pegmatite and wall rocks are thoroughly weathered and cut by a large number 
of landslip surfaces. The workings are decidedly unsafe, and inspection was made as brief as possible. 

As shown in figure 13, the adit intersects two pegmatite bodies. The larger, an irregular lens trend- 
ing nearly north and dipping west, is exposed in the drifts for a distance of 32 feet. It has a maximum 
exposed width of 10 feet. The other pegmatite trends north-northwest, dips steeply west, and is 3 to 4 feet 
thick. The larger pegmatite body is intersected by three faults that trend north-northeast to east-north- 
east and dip steeply west or northwest. 

In contrast to the pegmatites exposed in the middle and upper workings, the two bodies in the adit con- 
sist entirely of coarse to very coarse (crystals up to 4 feet long) perthite and plagioclase, the plagioclase 
completely kaolinized, the perthite little affected by weathering. Biotite and fine-grained muscovite are the 
only other minerals. The writer was unable to find a single grain of quartz in either pegmatite, although 
the dump shows pieces of quartz similar to those found in perthite-quartz zones. The feldspars have rag- 
ged boundaries against one another. It is possible that in part the original plagioclase formed by replace- 
ment of perthite. 

Whether either of the pegmatite bodies intersected by the adit is connected upward with the pegmatite 
exposed in the other workings is uncertain. In any event, no large tonnage of feldspar appears to be pres- 
ent at the prospect. 

NICHOLS PROSPECT 

On the divide separating Bryson Branch from Toot Hollow Branch, 3,100 feet N. 62° E. of Franklin 
Grove Church, there is a pegmatite that was evidently prospected many years ago for kaolin (pi. 1, no. 24). 
The part of the pegmatite body on the land of W. C. Nichols of Bryson City was prospected for feldspar by 
Mr. Nichols early in 1947. In January 1947 the old workings consisted of an open cut and three cross- 
trenches extending 250 feet N. 75° W. from a point 75 feet east of the ridge crest. By April 1947 a bulldozer 
had been used to clean out the westernmost cross-trench, so that nearly the full width of the pegmatite was 
exposed. 

The pegmatite is evidently a steeply dipping tabular body strking about N. 75° W. and cutting granitic 
gneiss. In the westernmost trench, the only place where the pegmatite is exposed to any extent, the north 
wall of the body dips 82° S., and the south wall dips 62° N. The attitudes of the contacts therefore suggest 
that the pegmatite pinches out downward, but only a few feet of each contact is exposed. 



Feldspar Deposits of the Bryson City District, North Carolina 93 

The exposed width of the pegmatite in the trench is about 27 feet. Along the north wall there is a 1- to 
2-inch border zone of fine- to medium-grained plagioclase-quartz-perthite pegmatite. Inside this zone is a 
wall zone of medium- to coarse-grained blocky plagioclase with minor amounts of blocky perthite and quartz. 
This zone is succeeded by an intermediate zone of medium- to coarse-grained plagioclase with quartz in 
graphic intergrowth, accompanied by scattered crystals of perthite. Next' is an inner intermediate zone 
(core margin zone) 7 feet thick, composed of perthite crystals up to 2 feet in diameter, with subordinate 
interstitial quartz. The apparent core of the pegmatite is 7 feet wide and consists of massive quartz with 
sparsely scattered crystal of perthite. The remainder of the pegmatite, between the core and the south wall, 
was covered with debris to such an extent that its internal structure could not be determined. It is about 
9 feet wide and appears similar in general to the feldspathic zones north of the core, except that kaolinized 
plagioclase appears in the core-margin zone. 

All plagioclase originally present in the pegmatite has been weathered to kaolin, and even the perthite 
has become friable. 

Little can be seen of the pegmatite outside the trench. Scattered blocks of massive quartz are strewn 
over the surface for 30 feet westward along strike, and massive quartz evidently derived from the core forms 
an outcrop at the summit of the ridge, 150 feet eastward along the strike. The width and full length of the 
pegmatite body are still largely unknown. Information available does not suggest the presence of a pegma- 
tite body large enough to yield any great tonnage of feldspar, but small-scale operations in the core-margin 
zone below the limit of kaolinization of plagioclase might yield a moderate tonnage of high-grade material. 
Before the possibility can be accurately appraised, however, systematic prospecting to determine the ex- 
tent, continuity, and average thickness of the core-margin zone should be done. 

BALL NO. 1 MINE 

The Ball No. 1 mine (pi. 1, no. 25) lies 1,850 feet N. 70° W. of Watkins cemetery, on the slope overlook- 
ing the road that extends west of the cemetery. The land is owned by Mrs. Lura Ball of Bryson City. The 
Blue Ridge Mining Co. leased and operated the property in 1938 and 1939 and made two adjoining open 
cuts. The north cut is now about 55 feet long, 25 to 50 feet wide, and 35 feet in maximum depth. A cross- 
cut at the northeast corner of the working gives access to the floor. Much material has slumped from the 
walls, and the original depth is uncertain. The south open cut trends N. 78° E. It is 65 feet long, 10 to 30 
feet wide, and probably 40 feet in maximum depth. 

The pegmatite is a steeply dipping body that is about 27 feet thick in the northern part of the north 
open cut. In this cut the east contact of the pegmatite strikes N. 13° W. and dips 85° E. ; the west contact 
strikes N. 31° E and dips 72° to 88° E. Upward from the floor of the open cut the west contact is displaced 
eastward by successive gently dipping landslip surfaces. The ground north of the open cut is broken, and 
it is evident that much of the hill slope has been involved in landsliding. 

The pegmatite shows a thin border zone of fine-grained plagioclase-quartz-perthite pegmatite. The 
remainder of the material exposed is a coarse to very coarse mixture of plagioclase, quartz, and perthite, 
with abundant accessory biotite in strip-shaped crystals and scattered books. The feldspars occur in crys- 
tals with quartz in graphic intergrowth and also in crystals partly or entirely free of intergrown quartz. 
Graphic intergrowths of plagioclase with quartz are abundant. The material exposed in the south open cut 
is similar. 

The wall rock in the north open cut is border gneiss. In the south open cut the east wall of the pegma- 
tite is granitic gneiss. The west wall is not exposed but is probably border gneiss. The foliation of the 
border gneiss in the north cut strikes N. 34° E. and dips 85° to 89° W. It is evident that the pegmatite is 
a discordant body cutting across the local trends of the belts of older rocks. 

Both wall rocks and pegmatites are in an advanced stage of weathering. Plagioclase has been wholly 
converted to kaolin, biotite is partly oxidized to limonite and altered to clay, and the wall rocks are soft and 
crumbly. 

According to local report, mining was discontinued owing to the failure to discover a shoot of high- 
grade feldspar. Much of the feldspar in the pegmatite is so heavily intergrown with quartz that even if 
unweathered it would not yield a satisfactory proportion of commercial feldspar. 



94 Feldspar Deposits of the Bryson City District, North Carolina 

Eighty feet S. 22° W. of the south open cut is a small pit in a narrow lens of pegmatite that strikes N. 
46° W. and dips 73° NE. The pegmatite cuts across the contact of border gneiss and granitic gneiss, the 
contact and the foliation of the gneisses striking N. 47° E. and dipping 75° NW. The pegmatite is a coarse 
mixture of plagioclase, perthite, and quartz, with the coarsest material in the center of the lens. 

HANS MINE 

The Hans mine (pi. 1, no. 26), also known as the Thomas mine, lies 2,600 feet N. 38° W. of Mount Car- 
mel Church, at the end of a high spur overlooking the valley of Messer Branch. According to Mr. G. L. Crisp 
of Bryson City, the mine was worked for kaolin by Doc* Hans from 1918 to 1920. The clay was mixed with 
water and flumed down Messer Branch to Buckner Branch, thence down Buckner Branch to its mouth and 
across the Tuckasegee River to a small plant on the north bank beside the railroad. The clay was formed 
into small blocks at the plant. 

Workings consist of a northeasterly trending open cut roughly 240 feet long, 50 to 150 feet wide, and 15 
to 50 feet deep. Three crosscuts through the east side of the open cut furnish access to the floor. There 
are said to be a series of shafts sunk in the floor of the cut, but they are concealed beneath debris. A short 
distance south of the open cut is a trench, 15 feet long and 9 feet wide, trending parallel to the cut and prob- 
ably leading to a short adit. 

The country rock at the mine consists of weathered interbedded mica quartzites and quartz-mica schists. 
At the south end of the cut the foliation of these rocks strikes N. 13° E. and dips 73° W.; in the north cross- 
cut the foliation strikes N. 20° E. and dips 75° W. A series of lenses of pegmatite enclosed in these rocks 
appears to have been worked in the mine. Four lenses, each ranging in thickness from 1 foot to 12 feet, were 
exposed in the walls of the main cut and in the crosscuts at the time of inspection. The largest, exposed in 
the north and middle crosscuts, apparently ranges from 1 foot to 12 feet in thickness. In the middle cross- 
cut it strikes N. 43° E., dips 56° to 77° NW., and is concordant in general with the foliation of the en- 
closing metasedimentary rocks. In addition to a thin border zone, it shows a wall zone 1 foot to 2 feet 
thick composed of medium-grained plagioclase-quartz pegmatite with accessory muscovite. Inside this zone 
is an apparent core of blocky perthite and plagioclase with subordinate quartz and accessory muscovite in 
ruled striplike crystals up to a foot long and an inch thick. The part of the pegmatite along the hanging 
wall (northwest wall) is obscured by debris, but apparently the wall zone is present there as it is along 
the footwall. 

Whether larger bodies of pegmatite were found in the open cut during mining is not known. Pres- 
ent exposures in the workings offer little encouragement to the feldspar prospector. 

HARRISON T. CRISP PROSPECT 

The Harrison T. Crisp prospect (pi. 1, no. 28) lies 2,100 feet N. 80° W. of Mount Carmel Church on 
land owned by Mr. Harrison T. Crisp of Bryson City. The prospect lies on the south slope of the first val- 
ley north of the valley of Gibby Branch. Development work was done by the owner in 1946. 

The main working is an adit, the portal of which is just above the bottom of the valley. The adit ex- 
tends 65 feet S. 60° W. into the south wall of the valley. At 22 feet from the portal a 27-foot drift runs N. 
47° W. ; and at 46 feet, a 37-foot drift runs S. 32° E. A series of pits extends 300 feet S. 24° W. up the wall 
of the valley from the main working. One or more of these pits may be entrances to adits, now caved, that 
were evidently run many years ago. 

The workings suggest a single pegmatite body trending obliquely across the strike of the enclosing rocks. 
Pegmatite is exposed in contact with metasedimentary rocks in the northwest drift in the main working. The 
contact is uneven but has an average strike of N. 11° E. and an average dip of 80° W. The same contact was 
intersected 11 feet from the southwest end of the main adit. There it strikes about N. 35° E. and has a 
steep northwesterly dip. Rolls of the contact plunge gently southwest. In one of the southernmost pits 
pegmatite is exposed in contact with granite gneiss. 

The metasedimentary rocks adjacent to the contact in the main working in places are injected lit-par-lit 
by pegmatitic material. The pegmatite has only an indistinct zonal structure. A 1-inch border zone of fine- 



*True name, not nickname or title. 



Feldspar Deposits of the Bryson City District, North Carolina 95 

grained pegmatite is present adjacent to the contact. This zone is succeeded inward by a vaguely denned 
wall zone, 1 to 2 feet thick, composed of medium- to coarse-grained plagioclase-quartz-perthite pegmatite 
with minor amounts of biotite, in striplike crystals and accessory small red garnet crystals. Graphic inter- 
growths of both soda and potash feldspars with quartz are abundant. The perthite crystals are as much as 
3 feet in length. This material composes the walls of the southeast drift and the walls of the remainder of 
the workings except as noted above. 

The thickness of pegmatite exposed in the main working is between 30 and 35 feet, and the footwall 
contact is not exposed. The arrangement of pits south of the main working suggests a body of comparable 
or greater width, but exposures are too poor to give much information on the structure of this part of the 
pegmatite. A series of trenches across the strike of the pegmatite would entail little effort and would at 
least serve to determine whether a body of feldspar of commercial grade is present at surface level. The 
material exposed in the main adit is not of commercial grade. 

OGLE MINES 

The Ogle mines are located in the upper part of the valley of Buckner Branch, on land owned by Mr. 
M. C. Ogle of Bryson City. The lower mine (pi. 1, no. 29) is 1,375 feet N. 4° E. of Ogle Knob, the upper mine 
(pi. 1, no. 30) is 1,250 feet due north of the knob. According to Mr. Ogle, the mines were worked many 
years ago for kaolin by a man named Frost. The mines may be the ones referred to by Bayley 54 as worked 
by the Carolina Clay Co. some years prior to 1918. No production data are available, but the yield was prob- 
ably not great. 

The lower mine consists of an open cut about 85 feet long, 60 feet wide, and 8 to 40 feet deep, trending 
N. 75° W. into a hill slope. The headwall of the cut is composed of weathered granitic gneiss. Pegmatite is 
exposed for a distance of only 8 feet at the base of the headwall. The exposure is entirely massive quartz 
except for a crystal of perthite, 2 by 2 feet in size, near the north end. The dumps, however, show much per- 
thite of good quality and suggest the possibility that a perthite-rich zone is present in the pegmatite. 

The floor of the pit is approximately at the level of the branch and is separated from it by only a low 
ridge of debris. The drainage problem presented has thus far discouraged prospecting for feldspar. An 
additional difficulty is the unstable condition of the ground back of the headwall of the cut. The ground 
surface shows a number of low landslide scarps, and it is clear that a large part of the hillside is involved. 

The upper mine consists of an open cut trending S. 50° W. for 160 feet from its entrance. It is 15 to 
75 feet wide, and 5 to 50 feet deep ; maximum depth and width are at the southwest end. The northeast end 
and middle part of the cut are in granitic gneiss; the southwest end is in garnet-muscovite schist. At the 
contact, the schists are interlayered with muscovite granite gneiss through a thickness of 2 feet. 

Aside from a few narrow stringers of pegmatite in gneiss and schist, no pegmatite is exposed in the 
walls of the cut. The dumps, however, show pieces of massive quartz up to 1 inch in diameter, numerous 
pieces of perthite an inch or less in diameter, and fragments of kaolinized plagioclase. Exposures of the wall 
rock indicate that whatever pegmatite was worked must have been less than 20 feet thick over a substantial 
part of the length of the cut. 

DeHARTMINE 

The DeHart mine (pi. 1, no. 33) lies about 350 feet N. 31° W. of the position of Jackson Line Church 
(now moved) as shown on the map. It is on land owned by Mr. Daniel DeHart and is accessible from U. S. 
Highway 19 via gravel road leading to the owner's house. The mine was opened and operated by Mr. W. J. 
Alexander in 1939 and part of 1940. About 300 tons of high-grade potash feldspar was produced and ship- 
ped to Spruce Pine, N. C. 

The main or No. 1 working at the mine consists of an entrance cut extending 60 feet S. 60° E. to a partly 
filled northeast-trending open cut 44 feet long, 32 feet in maximum width, and 23 feet in maximum depth 
(pi. 19). A partly timbered shaft was sunk in the floor of the open cut to a depth reported as 20 feet, and 
from the bottom a drift 6 feet in width is said to extend in a southerly direction for a distance of about 100 
feet. The shaft was filled to within 13 feet of the surface in 1946. A drift into the southeast side of the 
54 Ries, H., Bayley, W. S., and others, High-grade clays of the eastern United States: U. S. Geol. Survey Bull. 708, p. 44, 1922. 



96 



Feldspar Deposits of the Bryson City District, North Carolina 



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Feldspar Deposits of the Bryson City District, North Carolina 97 

open cut was caved and inaccessible. Ninety feet S. 65° E. of the open cut is the No. 2 working, an adit with 
portal at 1,914 feet. The adit extends N. 65° W. for 80 feet, at this point apparently connecting, by means 
of a small hole, with the caved working run from the open cut. The No. 3 working is a small open cut that 
leads to an incline extending downward 32 feet N. 22° W. at an angle of about 20°. A trench extends 17 
feet N. 50° W. from the head wall of the open cut. The No. 4 working is an adit with portal southwest of the 
No. 3 working. It extends nearly north for 50 feet. At 40 feet from the portal, a sinuous, curving adit ex- 
tends about 60 feet northeast and north, at which place it is blocked by fill. Six feet from the end a raise 
extends 14 feet upward to the east at an angle of 35°, expanding into a small chamber. At 10 feet and 20 
feet south of the raise, short crosscut drifts have been run eastward from the main drift. Another small 
open cut west of the No. 2 working and three shallow pits complete the feldspar workings. Twenty-three 
postholes were put down in the course of mapping in order to outline the pegmatite and obtain additional 
information on its composition and internal structure. 

The principal pegmatite on the property is a north-trending body about 220 feet long and 90 feet in 
maximum width. About half-way along its length a branch about 25 to 30 feet wide extends southwest 
from the main body for a distance of at least 60 feet. The No. 1 and No. 2 workings are in the northern 
part of the pegmatite, but the drift run southward from the shaft in the main working may lie partly in the 
branch. The No. 3 and No. 4 workings are in the main body south of the point at which the pegmatite 
divides. Just south of the division point the main body appears to be 70 feet in maximum width, but it 
tapers irregularly southward toward the portal of the No. 4 working. 

The north part of the pegmatite is a blunt-nosed, discordant semi-lens with footwall dipping 33° to 45° 
W. and hanging wall dipping 56° to 68° W. The southern part of the main body is apparently much less 
regular in form. Both walls are highly irregular where exposed, and dips and strikes of the contacts vary 
widely within short distances. Although the outcrop width of the pegmatite is as much as 70 feet, the true 
thickness is probably nowhere more than 35 or 40 feet. At its southern end the pegmatite appears to fray 
out. Exposures in the cut-bank at the southern limit of the area mapped show an irregular network of 
pegmatite stringers, probably offshoots from the footwall of the main body. At 9 feet from the portal of the 
No. 4 working, the footwall intersects the adit floor. From this point to 22 feet from the portal it lies in 
places below the floor. At 22 feet it finally slopes downward beneath the floor, the contact there striking 
N. 82° W. and dipping 35° N. As shown in the plan of the working on plate 19, the hanging wall also is 
highly irregular. Many of the variations in the attitude of the contact are clearly fracture-controlled. 

The wall rock is a medium-grained linear to platy biotite granite gneiss. In the No. 2 working the 
irregular lower end of a pendant of biotite schist, 5 feet in maximum thickness, is exposed. Foliations in 
the schist and the gneiss are parallel, even where the contact of the two is nearly perpendicular to the folia- 
tion. The foliation of the granite gneiss within the area mapped strikes north to northeast in general and 
dips steeply west, but in part of the No. 4 working the strike is northwest and the dip steep southwest. 
Both gneiss and biotite schist are in an advanced stags of decomposition throughout the workings. 

A posthole 50 feet northwest of the trench at the No. 3 working disclosed a westward-dipping contact 
of pegmatite and granite gneiss. Nothing of the extent of this body or its relation to the main body is known. 
Probably it is of no great size. 

The main pegmatite consists of five zones : border and wall zones of plagioclase-quartz pegmatite with 
minor perthite, an outer intermediate zone of plagioclase-quartz-perthite pegmatite, an inner intermediate 
zone of perthite-plagioclase-quartz pegmatite, and a core of quartz-perthite pegmatite. The border zone is 
a Vi-inch to 1-inch layer of plagioclase-quartz-perthite pegmatite with accessory biotite. Contacts of the 
zone with granite gneiss are commonly sharp, but in a few places in the No. 4 working the contact is grada- 
tional over a width of 14 inch. The wall zone of the pegmatite is discontinuous. It is lacking entirely in 
the No. 1 working, but is present elsewhere and ranges from 14 foot to IV2 f ee t m thickness. It is medium- 
to coarse-grained (grain size 1/2 inch to 5 inches) and composed essentially of massive plagioclase and 
quartz, with scarce crystals of perthite, scattered flakes of biotite up to 1 inch broad and Vi inch thick, and 
accessory garnet in crystals up to 1 inch in diameter. In places the zone consists almost entirely of massive 
plagioclase. 

The outer intermediate zone is 4 to more than 15 feet thick and is composed of coarse-grained to very 
coarse-grained plagioclase-quartz-perthite pegmatite with accessory to minor biotite and accessory garnet. 



98 Feldspar Deposits of the Br.yson City District, North Carolina 

Plagioclase forms crystals up to 3 feet in diameter, massive or in irregular to graphic intergrowth with 
quartz. Biotite forms striplike crystals up to IV2 feet long, 4 inches broad, and y 2 inch thick. Muscovite is 
present in the north end of the No. 4 working in aggregates of small books, and in separate books up to 2 
inches broad. It is ruled, reeved, and cross-fractured, and fit only for mica scrap. 

The inner intermediate zone is composed of perthite-plagioclase-quartz pegmatite. It consists of two 
main segments, one forming a discontinuous envelope around the segment of the core exposed by the No. 1 
working, the other a similar envelope around the core segment explored in the No. 3 and No. 4 pegmatites. 

The segment of the inner intermediate zone exposed in the north workings consists of massive plagio- 
clase and perthite crystals up to 3 feet long and 2 feet broad, with subordinate interstitial quartz. The zone 
has a maximum thickness of at least 6 feet; it may have been thicker in mined-out parts of the pegmatite. 
Only the part of the zone on the hanging-wall side of the core is exposed. The core beneath it is a mixture 
of stout perthite crystals 3 feet to 6 feet long embedded in massive coarse quartz, which composes areas of 
the face of the open cut ranging from 1 foot by 3 feet to 6 by 5 feet. Perthite and quartz are present in ap- 
proximately equal proportions. Along its margins, strips, fans of strips, and slabby books of biotite 8 by 4 
inches by i/ 2 inch, up to 18 by 8 inches by 1 inch, cut quartz and feldspars along intersecting fractures. The 
keel of the core appears to be exposed in the shaft in the floor of the No. 1 working (section A- A', pi. 19), 
and calculation from this and from the data obtained in mapping would appear to indicate that the core is 
plunging about 40°-45° in a direction near S. 45° W. According to Mr. Alexander, the core and accompany- 
ing inner intermediate zone were followed by a tunnel southward for nearly 100 feet, at which point feldspar- 
rich rock pinched out. The course of this tunnel is uncertain. Material apparently belonging to the quartz- 
perthite zone was struck in a posthole put down 48 feet S. 18° E. of the shaft, but was found nowhere else 
in the vicinity. From this fact it appears that the feldspar-rich zones exposed in the No. 1 working extend- 
southward into the southwest branch of the pegmatite. In any event, they appear to be isolated from the 
segments of the two innermost zones exposed in the No. 3 and No. 4 workings. 

The core segment exposed in the No. 3 and No. 4 workings is an extremely irregular lens that ranges 
in thickness from a few inches to perhaps 8 feet, strikes north to N. 40° E., and dips 10° to nearly 55° W. to 
NW. It is similar in composition to the core segment of the north workings, but the ratio of quartz to per- 
thite varies. The quartz varies from gray and glassy to light gray, milky, and banded. The banding is 
exposed only at one point in the No. 4 working. At this point the core dips 10° NW., whereas the banding 
strikes N. 40° E. and dips 25° NW. The northern edge of the core was intersected in the inclined raise and 
small chamber at the northern end of the working, where it appears to plunge about 55° approximately- 
west-southwest. Twenty-four feet south of the inclined raise, the pegmatite is offset eastward by an oblique- 
slip reversal fault, with the downthrow on the north side. The offset part of the pegmatite appears in the 
walls of the drift 19 feet from the junction of drift and adit. Adit and drift appear to lie along the keel 
of the core, which here is nearly horizontal. In the west wall of the adit the core appears to be wedging out. 

Perthite-plagioclase-quartz pegmatite similar to that in the north working forms a zone V2 to 1 foot 
thick along the core in the No. 4 working, but is absent in the No. 3 working. At one point, thin offshoots 
of the core quartz extend into fractures in the marginal feldspar crystals. 

An odd feature of the pegmatite is the occurrence of a lens of quartz margined with massive plagioclase 
and perthite and fracture controlled biotite in the wall zone of the pegmatite in the No. 2 working (section 
A- A', pi. 19). The lens has a maximum length, parallel to the dip, of at least 5 feet, and a maximum thick- 
ness of 18 inches. Exposures give no explanation of this anomalous occurrence. The body does not ap- 
pear to be fracture-controlled. 

Aggregates of greenish, fine-grained muscovite disseminated in kaolin appear to have been formed at 
the expense of perthite in a few places. In the adit of the No. 4 working, there is a striking development of 
closely spaced garnet crystals along planar to sinuous surfaces that cut the pegmatite at high angles to the 
zonal structure. The principal planes strike N. 28° E. and dip about 70° NW. At one place in the adit, the 
garnets are thickly disseminated in feldspathic pegmatite along an inch- wide fracture-filling of quartz 1V4 
feet long. Garnet also is abundant here in scattered crystals 1/16 inch to 3 inches in diameter and in aggre- 
gates of crystals up to 5 inches by 1 by 14 inch. Garnet is evidently in large part a late mineral. Similar 
planar distribution of garnet is shown at several places in the drift. 



Feldspar Deposits of the Bryson City District, North Carolina 99 

Kaolin. — Except in the shaft in the No. 1 working, where plagioclase is only partly altered, all plagio- 
clase in the exposed parts of the pegmatite is completely kaojinized, and in many places weathering of 
perthite is sufficiently advanced so that the feldspar crumbles readily. The amount of kaolin present in 
the deposit is not readily estimated, but it seems unlikely that any large tonnage is present in so small a 
pegmatite body. Some of the kaolin is white and apparently pure. Most is intergrown with various pro- 
portions of quartz, and some is stained by limonite or iron oxides, or both, derived from garnet and biotite. 

Feldspar. — Feldspar obtained from the DeHart mine in 1939 and 1940 is said to have been of high qual- 
ity. Most of the production was from the No. 1 working. As plagioclase has been entirely kaolinized in 
most of the workings, the feldspar must have been entirely or almost entirely perthite. Perthite in the mine 
ranges from cream white where nearly fresh to buff where weathered. Limonite stains many crystals along 
crystal boundaries, fractures, and cleavage surfaces, but^t is not a serious defect, as much of this stain 
would be lost in crushing and washing. 

Development work in the southern part of the pegmatite has failed to discover perthite-quartz-plagio- 
clase and quartz-perthite zones of sufficient size to repay mining under current conditions. These zones are 
thicker in the north workings, and depending on how far they extend downplunge with the same thickness, 
may still contain a moderate tonnage of high-grade feldspar. At depth, moreover, as the bottom of the zone 
of weathering is reached and unaltered plagioclase appears, the proportion of recoverable feldspar in the 
perthite-plagioclase-quartz zone should rise. Some feldspar remains between the surface and the bottom of 
the drift run south from the shaft ; this would have to be extracted by stripping and open-cut mining, but 
Mr.. Alexander states that no stoping could be done from the drift because of the decomposed condition of 
the pegmatite. 

The location of reserves at depth depends on the plunge of the pegmatite. If the plunge suggested by 
mapping is correct, the feldspar-rich zones would be found farther south on each successively deeper level. 

PAYNE AND SULLIVAN MINE 

The payne and Sullivan mine (pi. 1, no. 35) lies 3,700 feet N. 5V2° E. of Cold Spring Church, on the 
crest of the ridge east of Davis Branch. The mine is probably one of a group referred to by Pratt 55 as Hugh 
J. Sloan's mines on the property of A. J. Cunningham. Pratt reports that operation began in July 1916 and 
were still in progress a year later. Clay from the mines was trammed to the head of a flume 800 feet long, 
which carried the clay down the mountainside to a washing and pressing plant. The dried pressed kaolin 
was hauled by trams a mile to a siding on the Alarka Valley Railroad (on old lumber railroad). The mine 
here discussed as the Payne and Sullivan mine is apparently that described by Pratt as the vein first worked. 

Bayley 56 visited the mines in 1918, describing them under the name of Payne and Sullivan mine. He 
stated that the mines had been closed down by the previous lessees (presumably Sloan) several years before 
his visit, after some 250 tons of washed kaolin had been recovered. Bayley's pit No. 1 is the main working 
described below. 

The main working is an open cut 190 feet long, 20 to 50 feet wide, and about 35 feet in maximum depth. 
There is much debris over the floor. Bayley states that the kaolin was mined out to a maximum depth of 65 
feet except at the southwest end of the excavation, where terrace-like benches were left about 40 feet above 
the bottom of the pit. At the time the mine was abandoned material was being removed from the terrace 
with the aid of two shafts. At the west end of the terrace there was a cliff 40 feet high pierced by a tun- 
nel. Both cliff and tunnel were said to show kaolin. Slump has destroyed all evidence of tunnel and shafts. 
Bayley states that the southeast contact of pegmatite with the enclosing granitic gneiss was vertical so far 
as uncovered. The internal structure of the pegmatite, as exposed in 1947, likewise suggests a vertical body. 
Bayley states that the width of the deposit was 40 or 45 feet, but it is not clear whether by "deposit" he 
meant the whole pegmatite or merely the part worked for kaolin. The former would appear the more prob- 
able. The present exposed width, which does not include the southeast part of the pegmatite, is about 18 
feet. 



Pratt, J. H., The mining industry in North Carolina during 1913-17, inclusive: North Carolina Geol. and Econ. Survey, Econ. 
Paper no. 49, pp. 147-149 (report by J. E. Smith), 1919. 
' Ries, H., Bayley, W. S., and others, High-grade clays of the eastern United States: U. S. Geol. Survey Bull. 708, p. 44, 1922. 



100 Feldspar Deposits of the Bryson City District, North Carolina 

Along the west side of the pegmatite there is a wall zone 1 foot to 2 feet thick composed of medium- 
grained plagioclase and quartz with accessory biotite in books % to 1 inch broad. Inside this zone is an 
intermediate zone 2 to 3 feet thick composed of coarse, blocky plagioclase and perthite, plagioclase and per- 
thite in graphic intergrowth with quartz, and accessory biotite in small striplike crystals. Inside this zone, 
in turn, is a core-margin zone, a few inches thick, composed of kaolinized blocky plagioclase. The core of 
the pegmatite, 5 to probably 12 feet thick, is composed of massive quartz containing scattered stout crystals 
of perthite up to 5 feet in length. The core has been left in mining, and forms a prominent rib extending 
100 feet along the center of the working. The southwest end of the core is concealed. 

The open cut is deepest southeast of the core, indicating that this was the kaolin-rich part of the peg- 
matite. Whether this part of the pegmatite is sufficiently rich in feldspar below the limit of weathering 
cannot be determined. Parts of the pegmatite exposed at the time of visit offer little encouragement to the 
feldspar prospector. 










DATE DUE 




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GAYLORD 






PRINTED INU.S.A. 






JUL 1 8 1957